400 lines
13 KiB
C
400 lines
13 KiB
C
/* Locating a program in a given path.
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Copyright (C) 2001-2004, 2006-2021 Free Software Foundation, Inc.
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Written by Bruno Haible <haible@clisp.cons.org>, 2001, 2019.
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <https://www.gnu.org/licenses/>. */
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#include <config.h>
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/* Specification. */
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#include "findprog.h"
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#include <errno.h>
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#include <stdbool.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <sys/stat.h>
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#include "filename.h"
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#include "concat-filename.h"
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#if (defined _WIN32 && !defined __CYGWIN__) || defined __EMX__ || defined __DJGPP__
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/* Native Windows, OS/2, DOS */
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# define NATIVE_SLASH '\\'
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#else
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/* Unix */
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# define NATIVE_SLASH '/'
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#endif
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/* Separator in PATH like lists of pathnames. */
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#if (defined _WIN32 && !defined __CYGWIN__) || defined __EMX__ || defined __DJGPP__
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/* Native Windows, OS/2, DOS */
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# define PATH_SEPARATOR ';'
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#else
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/* Unix */
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# define PATH_SEPARATOR ':'
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#endif
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/* The list of suffixes that the execlp/execvp function tries when searching
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for the program. */
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static const char * const suffixes[] =
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{
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#if defined _WIN32 && !defined __CYGWIN__ /* Native Windows */
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"", ".com", ".exe", ".bat", ".cmd"
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/* Note: Files without any suffix are not considered executable. */
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/* Note: The cmd.exe program does a different lookup: It searches according
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to the PATHEXT environment variable.
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See <https://stackoverflow.com/questions/7839150/>.
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Also, it executes files ending in .bat and .cmd directly without letting
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the kernel interpret the program file. */
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#elif defined __CYGWIN__
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"", ".exe", ".com"
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#elif defined __EMX__
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"", ".exe"
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#elif defined __DJGPP__
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"", ".com", ".exe", ".bat"
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#else /* Unix */
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""
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#endif
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};
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const char *
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find_in_given_path (const char *progname, const char *path,
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const char *directory, bool optimize_for_exec)
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{
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{
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bool has_slash = false;
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{
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const char *p;
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for (p = progname; *p != '\0'; p++)
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if (ISSLASH (*p))
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{
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has_slash = true;
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break;
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}
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}
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if (has_slash)
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{
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/* If progname contains a slash, it is either absolute or relative to
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the current directory. PATH is not used. */
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if (optimize_for_exec)
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/* The execl/execv/execlp/execvp functions will try the various
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suffixes anyway and fail if no executable is found. */
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return progname;
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else
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{
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/* Try the various suffixes and see whether one of the files
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with such a suffix is actually executable. */
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int failure_errno;
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size_t i;
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const char *directory_as_prefix =
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(directory != NULL && IS_RELATIVE_FILE_NAME (progname)
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? directory
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: "");
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#if defined _WIN32 && !defined __CYGWIN__ /* Native Windows */
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const char *progbasename;
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{
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const char *p;
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progbasename = progname;
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for (p = progname; *p != '\0'; p++)
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if (ISSLASH (*p))
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progbasename = p + 1;
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}
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bool progbasename_has_dot = (strchr (progbasename, '.') != NULL);
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#endif
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/* Try all platform-dependent suffixes. */
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failure_errno = ENOENT;
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for (i = 0; i < sizeof (suffixes) / sizeof (suffixes[0]); i++)
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{
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const char *suffix = suffixes[i];
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#if defined _WIN32 && !defined __CYGWIN__ /* Native Windows */
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/* File names without a '.' are not considered executable, and
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for file names with a '.' no additional suffix is tried. */
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if ((*suffix != '\0') != progbasename_has_dot)
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#endif
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{
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/* Concatenate directory_as_prefix, progname, suffix. */
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char *progpathname =
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concatenated_filename (directory_as_prefix, progname,
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suffix);
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if (progpathname == NULL)
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return NULL; /* errno is set here */
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/* On systems which have the eaccess() system call, let's
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use it. On other systems, let's hope that this program
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is not installed setuid or setgid, so that it is ok to
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call access() despite its design flaw. */
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if (eaccess (progpathname, X_OK) == 0)
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{
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/* Check that the progpathname does not point to a
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directory. */
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struct stat statbuf;
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if (stat (progpathname, &statbuf) >= 0)
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{
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if (! S_ISDIR (statbuf.st_mode))
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{
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/* Found! */
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if (strcmp (progpathname, progname) == 0)
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{
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free (progpathname);
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return progname;
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}
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else
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return progpathname;
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}
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errno = EACCES;
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}
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}
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if (errno != ENOENT)
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failure_errno = errno;
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free (progpathname);
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}
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}
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#if defined _WIN32 && !defined __CYGWIN__ /* Native Windows */
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if (failure_errno == ENOENT && !progbasename_has_dot)
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{
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/* In the loop above, we skipped suffix = "". Do this loop
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round now, merely to provide a better errno than ENOENT. */
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char *progpathname =
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concatenated_filename (directory_as_prefix, progname, "");
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if (progpathname == NULL)
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return NULL; /* errno is set here */
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if (eaccess (progpathname, X_OK) == 0)
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{
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struct stat statbuf;
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if (stat (progpathname, &statbuf) >= 0)
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{
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if (! S_ISDIR (statbuf.st_mode))
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errno = ENOEXEC;
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else
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errno = EACCES;
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}
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}
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failure_errno = errno;
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free (progpathname);
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}
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#endif
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errno = failure_errno;
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return NULL;
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}
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}
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}
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if (path == NULL)
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/* If PATH is not set, the default search path is implementation dependent.
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In practice, it is treated like an empty PATH. */
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path = "";
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{
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/* Make a copy, to prepare for destructive modifications. */
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char *path_copy = strdup (path);
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if (path_copy == NULL)
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return NULL; /* errno is set here */
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int failure_errno;
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char *path_rest;
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char *cp;
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#if defined _WIN32 && !defined __CYGWIN__ /* Native Windows */
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bool progname_has_dot = (strchr (progname, '.') != NULL);
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#endif
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failure_errno = ENOENT;
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for (path_rest = path_copy; ; path_rest = cp + 1)
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{
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const char *dir;
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bool last;
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char *dir_as_prefix_to_free;
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const char *dir_as_prefix;
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size_t i;
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/* Extract next directory in PATH. */
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dir = path_rest;
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for (cp = path_rest; *cp != '\0' && *cp != PATH_SEPARATOR; cp++)
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;
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last = (*cp == '\0');
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*cp = '\0';
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/* Empty PATH components designate the current directory. */
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if (dir == cp)
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dir = ".";
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/* Concatenate directory and dir. */
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if (directory != NULL && IS_RELATIVE_FILE_NAME (dir))
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{
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dir_as_prefix_to_free =
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concatenated_filename (directory, dir, NULL);
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if (dir_as_prefix_to_free == NULL)
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{
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/* errno is set here. */
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failure_errno = errno;
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goto failed;
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}
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dir_as_prefix = dir_as_prefix_to_free;
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}
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else
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{
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dir_as_prefix_to_free = NULL;
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dir_as_prefix = dir;
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}
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/* Try all platform-dependent suffixes. */
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for (i = 0; i < sizeof (suffixes) / sizeof (suffixes[0]); i++)
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{
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const char *suffix = suffixes[i];
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#if defined _WIN32 && !defined __CYGWIN__ /* Native Windows */
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/* File names without a '.' are not considered executable, and
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for file names with a '.' no additional suffix is tried. */
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if ((*suffix != '\0') != progname_has_dot)
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#endif
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{
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/* Concatenate dir_as_prefix, progname, and suffix. */
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char *progpathname =
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concatenated_filename (dir_as_prefix, progname, suffix);
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if (progpathname == NULL)
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{
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/* errno is set here. */
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failure_errno = errno;
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free (dir_as_prefix_to_free);
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goto failed;
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}
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/* On systems which have the eaccess() system call, let's
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use it. On other systems, let's hope that this program
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is not installed setuid or setgid, so that it is ok to
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call access() despite its design flaw. */
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if (eaccess (progpathname, X_OK) == 0)
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{
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/* Check that the progpathname does not point to a
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directory. */
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struct stat statbuf;
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if (stat (progpathname, &statbuf) >= 0)
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{
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if (! S_ISDIR (statbuf.st_mode))
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{
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/* Found! */
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if (strcmp (progpathname, progname) == 0)
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{
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free (progpathname);
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/* Add the "./" prefix for real, that
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concatenated_filename() optimized away.
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This avoids a second PATH search when the
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caller uses execl/execv/execlp/execvp. */
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progpathname =
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(char *) malloc (2 + strlen (progname) + 1);
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if (progpathname == NULL)
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{
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/* errno is set here. */
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failure_errno = errno;
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free (dir_as_prefix_to_free);
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goto failed;
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}
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progpathname[0] = '.';
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progpathname[1] = NATIVE_SLASH;
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memcpy (progpathname + 2, progname,
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strlen (progname) + 1);
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}
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free (dir_as_prefix_to_free);
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free (path_copy);
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return progpathname;
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}
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errno = EACCES;
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}
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}
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if (errno != ENOENT)
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failure_errno = errno;
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free (progpathname);
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}
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}
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#if defined _WIN32 && !defined __CYGWIN__ /* Native Windows */
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if (failure_errno == ENOENT && !progname_has_dot)
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{
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/* In the loop above, we skipped suffix = "". Do this loop
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round now, merely to provide a better errno than ENOENT. */
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char *progpathname =
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concatenated_filename (dir_as_prefix, progname, "");
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if (progpathname == NULL)
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{
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/* errno is set here. */
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failure_errno = errno;
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free (dir_as_prefix_to_free);
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goto failed;
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}
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if (eaccess (progpathname, X_OK) == 0)
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{
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struct stat statbuf;
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if (stat (progpathname, &statbuf) >= 0)
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{
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if (! S_ISDIR (statbuf.st_mode))
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errno = ENOEXEC;
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else
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errno = EACCES;
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}
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}
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failure_errno = errno;
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free (progpathname);
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}
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#endif
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free (dir_as_prefix_to_free);
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if (last)
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break;
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}
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failed:
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/* Not found in PATH. */
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free (path_copy);
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errno = failure_errno;
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return NULL;
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}
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}
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