mirror of
https://github.com/fish-shell/fish-shell.git
synced 2024-11-24 03:51:23 +08:00
599 lines
16 KiB
C++
599 lines
16 KiB
C++
/** \file postfork.cpp
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Functions that we may safely call after fork().
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*/
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#include <fcntl.h>
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#include "signal.h"
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#include "postfork.h"
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#include "iothread.h"
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#include "exec.h"
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/** The number of times to try to call fork() before giving up */
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#define FORK_LAPS 5
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/** The number of nanoseconds to sleep between attempts to call fork() */
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#define FORK_SLEEP_TIME 1000000
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/** Base open mode to pass to calls to open */
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#define OPEN_MASK 0666
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/** fork error message */
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#define FORK_ERROR "Could not create child process - exiting"
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/** file redirection clobbering error message */
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#define NOCLOB_ERROR "The file '%s' already exists"
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/** file redirection error message */
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#define FILE_ERROR "An error occurred while redirecting file '%s'"
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/** file descriptor redirection error message */
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#define FD_ERROR "An error occurred while redirecting file descriptor %s"
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/** pipe error */
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#define LOCAL_PIPE_ERROR "An error occurred while setting up pipe"
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/* Cover for debug_safe that can take an int. The format string should expect a %s */
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static void debug_safe_int(int level, const char *format, int val)
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{
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char buff[128];
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format_long_safe(buff, val);
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debug_safe(level, format, buff);
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}
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// PCA These calls to debug are rather sketchy because they may allocate memory. Fortunately they only occur if an error occurs.
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int set_child_group( job_t *j, process_t *p, int print_errors )
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{
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int res = 0;
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if( job_get_flag( j, JOB_CONTROL ) )
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{
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if (!j->pgid)
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{
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j->pgid = p->pid;
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}
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if( setpgid (p->pid, j->pgid) )
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{
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if( getpgid( p->pid) != j->pgid && print_errors )
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{
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char pid_buff[128];
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char job_id_buff[128];
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char getpgid_buff[128];
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char job_pgid_buff[128];
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format_long_safe(pid_buff, p->pid);
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format_long_safe(job_id_buff, j->job_id);
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format_long_safe(getpgid_buff, getpgid( p->pid));
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format_long_safe(job_pgid_buff, j->pgid);
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debug_safe( 1,
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"Could not send process %s, '%s' in job %s, '%s' from group %s to group %s",
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pid_buff,
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p->argv0_cstr(),
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job_id_buff,
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j->command_cstr(),
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getpgid_buff,
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job_pgid_buff );
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wperror( L"setpgid" );
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res = -1;
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}
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}
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}
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else
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{
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j->pgid = getpid();
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}
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if( job_get_flag( j, JOB_TERMINAL ) && job_get_flag( j, JOB_FOREGROUND ) )
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{
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if( tcsetpgrp (0, j->pgid) && print_errors )
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{
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char job_id_buff[128];
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format_long_safe(job_id_buff, j->job_id);
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debug_safe( 1, "Could not send job %s ('%s') to foreground", job_id_buff, j->command_cstr() );
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wperror( L"tcsetpgrp" );
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res = -1;
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}
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}
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return res;
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}
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/** Make sure the fd used by each redirection is not used by a pipe. */
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static void free_redirected_fds_from_pipes(io_chain_t &io_chain)
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{
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size_t max = io_chain.size();
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for (size_t i = 0; i < max; i++)
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{
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int fd_to_free = io_chain.at(i)->fd;
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/* We only have to worry about fds beyond the three standard ones */
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if (fd_to_free <= 2)
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continue;
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/* Make sure the fd is not used by a pipe */
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for (size_t j = 0; j < max; j++)
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{
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/* We're only interested in pipes */
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io_data_t *possible_conflict = io_chain.at(j);
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if (possible_conflict->io_mode != IO_PIPE && possible_conflict->io_mode != IO_BUFFER)
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continue;
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/* If the pipe is a conflict, dup it to some other value */
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for (int k=0; k<2; k++)
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{
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/* If it's not a conflict, we don't care */
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if (possible_conflict->param1.pipe_fd[k] != fd_to_free)
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continue;
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/* Repeat until we have a replacement fd */
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int replacement_fd = -1;
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while (replacement_fd < 0)
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{
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replacement_fd = dup(fd_to_free);
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if (replacement_fd == -1 && errno != EINTR)
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{
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debug_safe_int( 1, FD_ERROR, fd_to_free );
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wperror( L"dup" );
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FATAL_EXIT();
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}
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}
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possible_conflict->param1.pipe_fd[k] = replacement_fd;
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}
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}
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}
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}
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/**
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Set up a childs io redirections. Should only be called by
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setup_child_process(). Does the following: First it closes any open
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file descriptors not related to the child by calling
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close_unused_internal_pipes() and closing the universal variable
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server file descriptor. It then goes on to perform all the
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redirections described by \c io.
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\param io the list of IO redirections for the child
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\return 0 on sucess, -1 on failiure
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*/
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static int handle_child_io( io_chain_t &io_chain )
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{
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close_unused_internal_pipes( io_chain );
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free_redirected_fds_from_pipes(io_chain);
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for (size_t idx = 0; idx < io_chain.size(); idx++)
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{
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io_data_t *io = io_chain.at(idx);
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int tmp;
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if( io->io_mode == IO_FD && io->fd == io->param1.old_fd )
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{
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continue;
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}
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switch( io->io_mode )
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{
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case IO_CLOSE:
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{
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if( close(io->fd) )
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{
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debug_safe_int( 0, "Failed to close file descriptor %s", io->fd );
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wperror( L"close" );
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}
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break;
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}
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case IO_FILE:
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{
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// Here we definitely do not want to set CLO_EXEC because our child needs access
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if( (tmp=open( io->filename_cstr,
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io->param2.flags, OPEN_MASK ) )==-1 )
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{
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if( ( io->param2.flags & O_EXCL ) &&
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( errno ==EEXIST ) )
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{
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debug_safe( 1, NOCLOB_ERROR, io->filename_cstr );
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}
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else
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{
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debug_safe( 1, FILE_ERROR, io->filename_cstr );
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perror( "open" );
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}
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return -1;
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}
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else if( tmp != io->fd)
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{
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/*
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This call will sometimes fail, but that is ok,
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this is just a precausion.
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*/
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close(io->fd);
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if(dup2( tmp, io->fd ) == -1 )
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{
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debug_safe_int( 1, FD_ERROR, io->fd );
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perror( "dup2" );
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return -1;
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}
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exec_close( tmp );
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}
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break;
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}
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case IO_FD:
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{
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/*
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This call will sometimes fail, but that is ok,
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this is just a precausion.
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*/
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close(io->fd);
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if( dup2( io->param1.old_fd, io->fd ) == -1 )
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{
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debug_safe_int( 1, FD_ERROR, io->fd );
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wperror( L"dup2" );
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return -1;
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}
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break;
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}
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case IO_BUFFER:
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case IO_PIPE:
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{
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/* If write_pipe_idx is 0, it means we're connecting to the read end (first pipe fd). If it's 1, we're connecting to the write end (second pipe fd). */
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unsigned int write_pipe_idx = (io->is_input ? 0 : 1);
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/*
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debug( 0,
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L"%ls %ls on fd %d (%d %d)",
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write_pipe?L"write":L"read",
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(io->io_mode == IO_BUFFER)?L"buffer":L"pipe",
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io->fd,
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io->param1.pipe_fd[0],
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io->param1.pipe_fd[1]);
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*/
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if( dup2( io->param1.pipe_fd[write_pipe_idx], io->fd ) != io->fd )
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{
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debug_safe( 1, LOCAL_PIPE_ERROR );
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perror( "dup2" );
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return -1;
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}
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if (io->param1.pipe_fd[0] >= 0)
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exec_close( io->param1.pipe_fd[0]);
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if (io->param1.pipe_fd[1] >= 0)
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exec_close( io->param1.pipe_fd[1]);
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break;
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}
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}
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}
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return 0;
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}
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int setup_child_process( job_t *j, process_t *p )
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{
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bool ok=true;
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if( p )
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{
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ok = (0 == set_child_group( j, p, 1 ));
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}
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if( ok )
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{
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ok = (0 == handle_child_io( j->io ));
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if( p != 0 && ! ok )
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{
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exit_without_destructors( 1 );
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}
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}
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/* Set the handling for job control signals back to the default. */
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if( ok )
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{
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signal_reset_handlers();
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}
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/* Remove all signal blocks */
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signal_unblock();
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return ok ? 0 : -1;
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}
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int g_fork_count = 0;
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/**
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This function is a wrapper around fork. If the fork calls fails
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with EAGAIN, it is retried FORK_LAPS times, with a very slight
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delay between each lap. If fork fails even then, the process will
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exit with an error message.
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*/
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pid_t execute_fork(bool wait_for_threads_to_die)
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{
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ASSERT_IS_MAIN_THREAD();
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if (wait_for_threads_to_die) {
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/* Make sure we have no outstanding threads before we fork. This is a pretty sketchy thing to do here, both because exec.cpp shouldn't have to know about iothreads, and because the completion handlers may do unexpected things. */
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iothread_drain_all();
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}
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pid_t pid;
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struct timespec pollint;
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int i;
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g_fork_count++;
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for( i=0; i<FORK_LAPS; i++ )
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{
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pid = fork();
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if( pid >= 0)
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{
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return pid;
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}
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if( errno != EAGAIN )
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{
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break;
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}
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pollint.tv_sec = 0;
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pollint.tv_nsec = FORK_SLEEP_TIME;
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/*
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Don't sleep on the final lap - sleeping might change the
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value of errno, which will break the error reporting below.
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*/
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if( i != FORK_LAPS-1 )
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{
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nanosleep( &pollint, NULL );
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}
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}
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debug_safe( 0, FORK_ERROR );
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wperror (L"fork");
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FATAL_EXIT();
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return 0;
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}
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#if FISH_USE_POSIX_SPAWN
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bool fork_actions_make_spawn_properties(posix_spawnattr_t *attr, posix_spawn_file_actions_t *actions, job_t *j, process_t *p)
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{
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/* Initialize the output */
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if (posix_spawnattr_init(attr) != 0) {
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return false;
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}
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if (posix_spawn_file_actions_init(actions) != 0) {
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posix_spawnattr_destroy(attr);
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return false;
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}
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bool should_set_parent_group_id = false;
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int desired_parent_group_id = 0;
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if (job_get_flag(j, JOB_CONTROL))
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{
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should_set_parent_group_id = true;
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// PCA: I'm quite fuzzy on process groups,
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// but I believe that the default value of 0
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// means that the process becomes its own
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// group leader, which is what set_child_group did
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// in this case. So we want this to be 0 if j->pgid is 0.
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desired_parent_group_id = j->pgid;
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}
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/* Set the handling for job control signals back to the default. */
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bool reset_signal_handlers = true;
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/* Remove all signal blocks */
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bool reset_sigmask = true;
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/* Set our flags */
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short flags = 0;
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if (reset_signal_handlers)
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flags |= POSIX_SPAWN_SETSIGDEF;
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if (reset_sigmask)
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flags |= POSIX_SPAWN_SETSIGMASK;
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if (should_set_parent_group_id)
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flags |= POSIX_SPAWN_SETPGROUP;
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int err = 0;
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if (! err)
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err = posix_spawnattr_setflags(attr, flags);
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if (! err && should_set_parent_group_id)
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err = posix_spawnattr_setpgroup(attr, desired_parent_group_id);
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/* Everybody gets default handlers */
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if (! err && reset_signal_handlers)
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{
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sigset_t sigdefault;
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get_signals_with_handlers(&sigdefault);
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err = posix_spawnattr_setsigdefault(attr, &sigdefault);
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}
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/* No signals blocked */
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sigset_t sigmask;
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sigemptyset(&sigmask);
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if (! err && reset_sigmask)
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err = posix_spawnattr_setsigmask(attr, &sigmask);
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/* Make sure that our pipes don't use an fd that the redirection itself wants to use */
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free_redirected_fds_from_pipes(j->io);
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/* Close unused internal pipes */
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std::vector<int> files_to_close;
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get_unused_internal_pipes(files_to_close, j->io);
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for (size_t i = 0; ! err && i < files_to_close.size(); i++)
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{
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err = posix_spawn_file_actions_addclose(actions, files_to_close.at(i));
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}
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for (size_t idx = 0; idx < j->io.size(); idx++)
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{
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const io_data_t *io = j->io.at(idx);
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if( io->io_mode == IO_FD && io->fd == io->param1.old_fd )
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{
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continue;
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}
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if( io->fd > 2 )
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{
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/* Make sure the fd used by this redirection is not used by e.g. a pipe. */
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// free_fd(io_chain, io->fd );
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// PCA I don't think we need to worry about this. fd redirection is pretty uncommon anyways.
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}
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switch (io->io_mode)
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{
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case IO_CLOSE:
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{
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if (! err)
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err = posix_spawn_file_actions_addclose(actions, io->fd);
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break;
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}
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case IO_FILE:
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{
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if (! err)
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err = posix_spawn_file_actions_addopen(actions, io->fd, io->filename_cstr, io->param2.flags /* mode */, OPEN_MASK);
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break;
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}
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case IO_FD:
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{
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if (! err)
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err = posix_spawn_file_actions_adddup2(actions, io->param1.old_fd /* from */, io->fd /* to */);
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break;
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}
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case IO_BUFFER:
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case IO_PIPE:
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{
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unsigned int write_pipe_idx = (io->is_input ? 0 : 1);
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int from_fd = io->param1.pipe_fd[write_pipe_idx];
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int to_fd = io->fd;
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if (! err)
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err = posix_spawn_file_actions_adddup2(actions, from_fd, to_fd);
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if( write_pipe_idx > 0 )
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{
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if (! err)
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err = posix_spawn_file_actions_addclose(actions, io->param1.pipe_fd[0]);
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if (! err)
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err = posix_spawn_file_actions_addclose(actions, io->param1.pipe_fd[1]);
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}
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else
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{
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if (! err)
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err = posix_spawn_file_actions_addclose(actions, io->param1.pipe_fd[0]);
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}
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break;
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}
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}
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}
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/* Clean up on error */
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if (err) {
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posix_spawnattr_destroy(attr);
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posix_spawn_file_actions_destroy(actions);
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}
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return ! err;
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}
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#endif //FISH_USE_POSIX_SPAWN
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void safe_report_exec_error(int err, const char *actual_cmd, char **argv, char **envv)
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{
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debug_safe( 0, "Failed to execute process '%s'. Reason:", actual_cmd );
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switch( err )
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{
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case E2BIG:
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{
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char sz1[128], sz2[128];
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long arg_max = -1;
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size_t sz = 0;
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char **p;
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for(p=argv; *p; p++)
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{
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sz += strlen(*p)+1;
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}
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for(p=envv; *p; p++)
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{
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sz += strlen(*p)+1;
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}
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format_size_safe(sz1, sz);
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arg_max = sysconf( _SC_ARG_MAX );
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if( arg_max > 0 )
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{
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format_size_safe(sz2, sz);
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debug_safe(0, "The total size of the argument and environment lists %s exceeds the operating system limit of %s.", sz1, sz2);
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}
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|
else
|
|
{
|
|
debug_safe( 0, "The total size of the argument and environment lists (%s) exceeds the operating system limit.", sz1);
|
|
}
|
|
|
|
debug_safe(0, "Try running the command again with fewer arguments.");
|
|
break;
|
|
}
|
|
|
|
case ENOEXEC:
|
|
{
|
|
/* Hope strerror doesn't allocate... */
|
|
const char *err = strerror(errno);
|
|
debug_safe(0, "exec: %s", err);
|
|
|
|
debug_safe(0, "The file '%s' is marked as an executable but could not be run by the operating system.", actual_cmd);
|
|
break;
|
|
}
|
|
|
|
case ENOENT:
|
|
{
|
|
char interpreter_buff[128] = {}, *interpreter;
|
|
interpreter = get_interpreter(actual_cmd, interpreter_buff, sizeof interpreter_buff);
|
|
if( interpreter && 0 != access( interpreter, X_OK ) )
|
|
{
|
|
debug_safe(0, "The file '%s' specified the interpreter '%s', which is not an executable command.", actual_cmd, interpreter );
|
|
}
|
|
else
|
|
{
|
|
debug_safe(0, "The file '%s' or a script or ELF interpreter does not exist, or a shared library needed for file or interpreter cannot be found.", actual_cmd);
|
|
}
|
|
break;
|
|
}
|
|
|
|
case ENOMEM:
|
|
{
|
|
debug_safe(0, "Out of memory");
|
|
break;
|
|
}
|
|
|
|
default:
|
|
{
|
|
/* Hope strerror doesn't allocate... */
|
|
const char *err = strerror(errno);
|
|
debug_safe(0, "exec: %s", err);
|
|
|
|
// debug(0, L"The file '%ls' is marked as an executable but could not be run by the operating system.", p->actual_cmd);
|
|
break;
|
|
}
|
|
}
|
|
}
|