fish-shell/src/builtin_math.cpp
Fabian Homborg 9fc3d1215b [math] Check for runtime errors
When number is infinite, not a number, larger than LONG_MAX or smaller
than LONG_MIN, print a corresponding error and return STATUS_CMD_ERROR.

This should fix the worst of the problems, by at least making them clear.

Fixes #4479.
Fixes #4768.
2018-03-07 18:03:44 +01:00

217 lines
7.7 KiB
C++

// Implementation of the math builtin.
#include "config.h" // IWYU pragma: keep
#include <errno.h>
#include <stddef.h>
#include <algorithm>
#include <cmath>
#include <string>
#include "tinyexpr.h"
#include "builtin.h"
#include "builtin_math.h"
#include "common.h"
#include "fallback.h" // IWYU pragma: keep
#include "io.h"
#include "wgetopt.h"
#include "wutil.h" // IWYU pragma: keep
struct math_cmd_opts_t {
bool print_help = false;
int scale = 0;
};
// This command is atypical in using the "+" (REQUIRE_ORDER) option for flag parsing.
// This is needed because of the minus, `-`, operator in math expressions.
static const wchar_t *short_options = L"+:hs:";
static const struct woption long_options[] = {{L"scale", required_argument, NULL, 's'},
{L"help", no_argument, NULL, 'h'},
{NULL, 0, NULL, 0}};
static int parse_cmd_opts(math_cmd_opts_t &opts, int *optind, //!OCLINT(high ncss method)
int argc, wchar_t **argv, parser_t &parser, io_streams_t &streams) {
const wchar_t *cmd = L"math";
int opt;
wgetopter_t w;
while ((opt = w.wgetopt_long(argc, argv, short_options, long_options, NULL)) != -1) {
switch (opt) {
case 's': {
opts.scale = fish_wcstoi(w.woptarg);
if (errno || opts.scale < 0 || opts.scale > 15) {
streams.err.append_format(_(L"%ls: '%ls' is not a valid scale value\n"), cmd,
w.woptarg);
return STATUS_INVALID_ARGS;
}
break;
}
case 'h': {
opts.print_help = true;
break;
}
case ':': {
builtin_missing_argument(parser, streams, cmd, argv[w.woptind - 1]);
return STATUS_INVALID_ARGS;
}
case '?': {
// For most commands this is an error. We ignore it because a math expression
// can begin with a minus sign.
*optind = w.woptind - 1;
return STATUS_CMD_OK;
}
default: {
DIE("unexpected retval from wgetopt_long");
break;
}
}
}
*optind = w.woptind;
return STATUS_CMD_OK;
}
// We read from stdin if we are the second or later process in a pipeline.
static bool math_args_from_stdin(const io_streams_t &streams) {
return streams.stdin_is_directly_redirected;
}
/// Get the arguments from stdin.
static const wchar_t *math_get_arg_stdin(wcstring *storage, const io_streams_t &streams) {
std::string arg;
for (;;) {
char ch = '\0';
long rc = read_blocked(streams.stdin_fd, &ch, 1);
if (rc < 0) return NULL; // failure
if (rc == 0) { // EOF
if (arg.empty()) return NULL;
break;
}
if (ch == '\n') break; // we're done
arg += ch;
}
*storage = str2wcstring(arg);
return storage->c_str();
}
/// Return the next argument from argv.
static const wchar_t *math_get_arg_argv(int *argidx, wchar_t **argv) {
return argv && argv[*argidx] ? argv[(*argidx)++] : NULL;
}
/// Get the arguments from argv or stdin based on the execution context. This mimics how builtin
/// `string` does it.
static const wchar_t *math_get_arg(int *argidx, wchar_t **argv, wcstring *storage,
const io_streams_t &streams) {
if (math_args_from_stdin(streams)) {
return math_get_arg_stdin(storage, streams);
}
return math_get_arg_argv(argidx, argv);
}
static wcstring math_describe_error(te_error_t& error) {
if (error.position == 0) return L"NO ERROR?!?";
assert(error.type != TE_ERROR_NONE && L"Error has no position");
switch(error.type) {
case TE_ERROR_UNKNOWN_VARIABLE: return _(L"Unknown variable");
case TE_ERROR_MISSING_CLOSING_PAREN: return _(L"Missing closing parenthesis");
case TE_ERROR_MISSING_OPENING_PAREN: return _(L"Missing opening parenthesis");
case TE_ERROR_TOO_FEW_ARGS: return _(L"Too few arguments");
case TE_ERROR_TOO_MANY_ARGS: return _(L"Too many arguments");
case TE_ERROR_MISSING_OPERATOR: return _(L"Missing operator");
case TE_ERROR_UNKNOWN: return _(L"Expression is bogus");
default: return L"Unknown error";
}
}
/// Evaluate math expressions.
static int evaluate_expression(const wchar_t *cmd, parser_t &parser, io_streams_t &streams,
math_cmd_opts_t &opts, wcstring &expression) {
UNUSED(parser);
int retval = STATUS_CMD_OK;
te_error_t error;
std::string narrow_str = wcs2string(expression);
// Switch locale while computing stuff.
// This means that the "." is always the radix character,
// so numbers work the same across locales.
char *saved_locale = strdup(setlocale(LC_NUMERIC, NULL));
setlocale(LC_NUMERIC, "C");
double v = te_interp(narrow_str.c_str(), &error);
if (error.position == 0) {
// Check some runtime errors after the fact.
// TODO: Really, this should be done in tinyexpr
// (e.g. infinite is the result of "x / 0"),
// but that's much more work.
if (std::isinfinite(v)) {
streams.err.append_format(L"%ls: Error: Result is infinite\n", cmd);
streams.err.append_format(L"'%ls'\n", expression.c_str());
retval = STATUS_CMD_ERROR;
} else if (std::isnan(v)) {
streams.err.append_format(L"%ls: Error: Result is not a number\n", cmd);
streams.err.append_format(L"'%ls'\n", expression.c_str());
retval = STATUS_CMD_ERROR;
} else if (v >= LONG_MAX) {
streams.err.append_format(L"%ls: Error: Result is too large\n", cmd);
streams.err.append_format(L"'%ls'\n", expression.c_str());
retval = STATUS_CMD_ERROR;
} else if (v <= LONG_MIN) {
streams.err.append_format(L"%ls: Error: Result is too small\n", cmd);
streams.err.append_format(L"'%ls'\n", expression.c_str());
retval = STATUS_CMD_ERROR;
} else if (opts.scale == 0) {
// Normal results
streams.out.append_format(L"%ld\n", static_cast<long>(v));
} else {
streams.out.append_format(L"%.*lf\n", opts.scale, v);
}
} else {
streams.err.append_format(L"%ls: Error: %ls\n", cmd, math_describe_error(error).c_str());
streams.err.append_format(L"'%ls'\n", expression.c_str());
streams.err.append_format(L"%*lc^\n", error.position - 1, L' ');
retval = STATUS_CMD_ERROR;
}
setlocale(LC_NUMERIC, saved_locale);
free(saved_locale);
return retval;
}
/// The math builtin evaluates math expressions.
int builtin_math(parser_t &parser, io_streams_t &streams, wchar_t **argv) {
wchar_t *cmd = argv[0];
int argc = builtin_count_args(argv);
math_cmd_opts_t opts;
int optind;
// Is this really the right way to handle no expression present?
// if (argc == 0) return STATUS_CMD_OK;
int retval = parse_cmd_opts(opts, &optind, argc, argv, parser, streams);
if (retval != STATUS_CMD_OK) return retval;
if (opts.print_help) {
builtin_print_help(parser, streams, cmd, streams.out);
return STATUS_CMD_OK;
}
wcstring expression;
wcstring storage;
while (const wchar_t *arg = math_get_arg(&optind, argv, &storage, streams)) {
if (!expression.empty()) expression.push_back(L' ');
expression.append(arg);
}
if (expression.empty()) {
streams.err.append_format(BUILTIN_ERR_MIN_ARG_COUNT1, L"math", 1, 0);
return STATUS_CMD_ERROR;
}
return evaluate_expression(cmd, parser, streams, opts, expression);
}