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Factor map_fd out of map_file

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Will enable us to map an already-opened file
This commit is contained in:
ridiculousfish 2017-02-06 10:09:31 -08:00
parent 83f386347f
commit b91a2dd0bb
2 changed files with 28 additions and 17 deletions
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38
src/history.cpp
View File

@ -923,24 +923,11 @@ void history_t::populate_from_mmap(void) {
}
}
/// Do a private, read-only map of the entirety of a history file with the given name. Returns true
/// if successful. Returns the mapped memory region by reference.
bool history_t::map_file(const wcstring &name, const char **out_map_start, size_t *out_map_len,
file_id_t *file_id) {
wcstring filename = history_filename(name, L"");
if (filename.empty()) {
bool history_t::map_fd(int fd, const char **out_map_start, size_t *out_map_len) const {
if (fd < 0) {
return false;
}
int fd = wopen_cloexec(filename, O_RDONLY);
if (fd == -1) {
return false;
}
bool result = false;
// Get the file ID if requested.
if (file_id != NULL) *file_id = file_id_for_fd(fd);
// Take a read lock to guard against someone else appending. This is released when the file
// is closed (below). We will read the file after releasing the lock, but that's not a
// problem, because we never modify already written data. In short, the purpose of this lock
@ -951,6 +938,7 @@ bool history_t::map_file(const wcstring &name, const char **out_map_start, size_
// unlikely because we only treat an item as valid if it has a terminating newline.
//
// Simulate a failing lock in chaos_mode.
bool result = false;
if (!chaos_mode) history_file_lock(fd, LOCK_SH);
off_t len = lseek(fd, 0, SEEK_END);
if (len != (off_t)-1) {
@ -966,6 +954,26 @@ bool history_t::map_file(const wcstring &name, const char **out_map_start, size_
}
}
if (!chaos_mode) history_file_lock(fd, LOCK_UN);
return result;
}
/// Do a private, read-only map of the entirety of a history file with the given name. Returns true
/// if successful. Returns the mapped memory region by reference.
bool history_t::map_file(const wcstring &name, const char **out_map_start, size_t *out_map_len,
file_id_t *file_id) const {
wcstring filename = history_filename(name, L"");
if (filename.empty()) {
return false;
}
int fd = wopen_cloexec(filename, O_RDONLY);
if (fd < 0) {
return false;
}
// Get the file ID if requested.
if (file_id != NULL) *file_id = file_id_for_fd(fd);
bool result = this->map_fd(fd, out_map_start, out_map_len);
close(fd);
return result;
}

7
src/history.h
View File

@ -192,8 +192,11 @@ class history_t {
// Do a private, read-only map of the entirety of a history file with the given name. Returns
// true if successful. Returns the mapped memory region by reference.
bool map_file(const wcstring &name, const char **out_map_start, size_t *out_map_len,
file_id_t *file_id);
bool map_file(const wcstring &name, const char **out_map_start,
size_t *out_map_len, file_id_t *file_id) const;
// Like map_file but takes a file descriptor
bool map_fd(int fd, const char **out_map_start, size_t *out_map_len) const;
// Whether we're in maximum chaos mode, useful for testing.
bool chaos_mode;