diff options
Diffstat (limited to 'lib/findprog-in.c')
| -rw-r--r-- | lib/findprog-in.c | 399 |
1 files changed, 399 insertions, 0 deletions
diff --git a/lib/findprog-in.c b/lib/findprog-in.c new file mode 100644 index 0000000..d0505fb --- /dev/null +++ b/lib/findprog-in.c @@ -0,0 +1,399 @@ +/* Locating a program in a given path. + Copyright (C) 2001-2004, 2006-2020 Free Software Foundation, Inc. + Written by Bruno Haible <haible@clisp.cons.org>, 2001, 2019. + + This program is free software: you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 3 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see <https://www.gnu.org/licenses/>. */ + + +#include <config.h> + +/* Specification. */ +#include "findprog.h" + +#include <errno.h> +#include <stdbool.h> +#include <stdlib.h> +#include <string.h> +#include <unistd.h> +#include <sys/stat.h> + +#include "filename.h" +#include "concat-filename.h" + +#if (defined _WIN32 && !defined __CYGWIN__) || defined __EMX__ || defined __DJGPP__ + /* Native Windows, OS/2, DOS */ +# define NATIVE_SLASH '\\' +#else + /* Unix */ +# define NATIVE_SLASH '/' +#endif + +/* Separator in PATH like lists of pathnames. */ +#if (defined _WIN32 && !defined __CYGWIN__) || defined __EMX__ || defined __DJGPP__ + /* Native Windows, OS/2, DOS */ +# define PATH_SEPARATOR ';' +#else + /* Unix */ +# define PATH_SEPARATOR ':' +#endif + +/* The list of suffixes that the execlp/execvp function tries when searching + for the program. */ +static const char * const suffixes[] = + { + #if defined _WIN32 && !defined __CYGWIN__ /* Native Windows */ + "", ".com", ".exe", ".bat", ".cmd" + /* Note: Files without any suffix are not considered executable. */ + /* Note: The cmd.exe program does a different lookup: It searches according + to the PATHEXT environment variable. + See <https://stackoverflow.com/questions/7839150/>. + Also, it executes files ending in .bat and .cmd directly without letting + the kernel interpret the program file. */ + #elif defined __CYGWIN__ + "", ".exe", ".com" + #elif defined __EMX__ + "", ".exe" + #elif defined __DJGPP__ + "", ".com", ".exe", ".bat" + #else /* Unix */ + "" + #endif + }; + +const char * +find_in_given_path (const char *progname, const char *path, + const char *directory, bool optimize_for_exec) +{ + { + bool has_slash = false; + { + const char *p; + + for (p = progname; *p != '\0'; p++) + if (ISSLASH (*p)) + { + has_slash = true; + break; + } + } + if (has_slash) + { + /* If progname contains a slash, it is either absolute or relative to + the current directory. PATH is not used. */ + if (optimize_for_exec) + /* The execl/execv/execlp/execvp functions will try the various + suffixes anyway and fail if no executable is found. */ + return progname; + else + { + /* Try the various suffixes and see whether one of the files + with such a suffix is actually executable. */ + int failure_errno; + size_t i; + + const char *directory_as_prefix = + (directory != NULL && IS_RELATIVE_FILE_NAME (progname) + ? directory + : ""); + + #if defined _WIN32 && !defined __CYGWIN__ /* Native Windows */ + const char *progbasename; + + { + const char *p; + + progbasename = progname; + for (p = progname; *p != '\0'; p++) + if (ISSLASH (*p)) + progbasename = p + 1; + } + + bool progbasename_has_dot = (strchr (progbasename, '.') != NULL); + #endif + + /* Try all platform-dependent suffixes. */ + failure_errno = ENOENT; + for (i = 0; i < sizeof (suffixes) / sizeof (suffixes[0]); i++) + { + const char *suffix = suffixes[i]; + + #if defined _WIN32 && !defined __CYGWIN__ /* Native Windows */ + /* File names without a '.' are not considered executable, and + for file names with a '.' no additional suffix is tried. */ + if ((*suffix != '\0') != progbasename_has_dot) + #endif + { + /* Concatenate directory_as_prefix, progname, suffix. */ + char *progpathname = + concatenated_filename (directory_as_prefix, progname, + suffix); + + if (progpathname == NULL) + return NULL; /* errno is set here */ + + /* On systems which have the eaccess() system call, let's + use it. On other systems, let's hope that this program + is not installed setuid or setgid, so that it is ok to + call access() despite its design flaw. */ + if (eaccess (progpathname, X_OK) == 0) + { + /* Check that the progpathname does not point to a + directory. */ + struct stat statbuf; + + if (stat (progpathname, &statbuf) >= 0) + { + if (! S_ISDIR (statbuf.st_mode)) + { + /* Found! */ + if (strcmp (progpathname, progname) == 0) + { + free (progpathname); + return progname; + } + else + return progpathname; + } + + errno = EACCES; + } + } + + if (errno != ENOENT) + failure_errno = errno; + + free (progpathname); + } + } + #if defined _WIN32 && !defined __CYGWIN__ /* Native Windows */ + if (failure_errno == ENOENT && !progbasename_has_dot) + { + /* In the loop above, we skipped suffix = "". Do this loop + round now, merely to provide a better errno than ENOENT. */ + + char *progpathname = + concatenated_filename (directory_as_prefix, progname, ""); + + if (progpathname == NULL) + return NULL; /* errno is set here */ + + if (eaccess (progpathname, X_OK) == 0) + { + struct stat statbuf; + + if (stat (progpathname, &statbuf) >= 0) + { + if (! S_ISDIR (statbuf.st_mode)) + errno = ENOEXEC; + else + errno = EACCES; + } + } + + failure_errno = errno; + + free (progpathname); + } + #endif + + errno = failure_errno; + return NULL; + } + } + } + + if (path == NULL) + /* If PATH is not set, the default search path is implementation dependent. + In practice, it is treated like an empty PATH. */ + path = ""; + + { + /* Make a copy, to prepare for destructive modifications. */ + char *path_copy = strdup (path); + if (path_copy == NULL) + return NULL; /* errno is set here */ + + int failure_errno; + char *path_rest; + char *cp; + + #if defined _WIN32 && !defined __CYGWIN__ /* Native Windows */ + bool progname_has_dot = (strchr (progname, '.') != NULL); + #endif + + failure_errno = ENOENT; + for (path_rest = path_copy; ; path_rest = cp + 1) + { + const char *dir; + bool last; + char *dir_as_prefix_to_free; + const char *dir_as_prefix; + size_t i; + + /* Extract next directory in PATH. */ + dir = path_rest; + for (cp = path_rest; *cp != '\0' && *cp != PATH_SEPARATOR; cp++) + ; + last = (*cp == '\0'); + *cp = '\0'; + + /* Empty PATH components designate the current directory. */ + if (dir == cp) + dir = "."; + + /* Concatenate directory and dir. */ + if (directory != NULL && IS_RELATIVE_FILE_NAME (dir)) + { + dir_as_prefix_to_free = + concatenated_filename (directory, dir, NULL); + if (dir_as_prefix_to_free == NULL) + { + /* errno is set here. */ + failure_errno = errno; + goto failed; + } + dir_as_prefix = dir_as_prefix_to_free; + } + else + { + dir_as_prefix_to_free = NULL; + dir_as_prefix = dir; + } + + /* Try all platform-dependent suffixes. */ + for (i = 0; i < sizeof (suffixes) / sizeof (suffixes[0]); i++) + { + const char *suffix = suffixes[i]; + + #if defined _WIN32 && !defined __CYGWIN__ /* Native Windows */ + /* File names without a '.' are not considered executable, and + for file names with a '.' no additional suffix is tried. */ + if ((*suffix != '\0') != progname_has_dot) + #endif + { + /* Concatenate dir_as_prefix, progname, and suffix. */ + char *progpathname = + concatenated_filename (dir_as_prefix, progname, suffix); + + if (progpathname == NULL) + { + /* errno is set here. */ + failure_errno = errno; + free (dir_as_prefix_to_free); + goto failed; + } + + /* On systems which have the eaccess() system call, let's + use it. On other systems, let's hope that this program + is not installed setuid or setgid, so that it is ok to + call access() despite its design flaw. */ + if (eaccess (progpathname, X_OK) == 0) + { + /* Check that the progpathname does not point to a + directory. */ + struct stat statbuf; + + if (stat (progpathname, &statbuf) >= 0) + { + if (! S_ISDIR (statbuf.st_mode)) + { + /* Found! */ + if (strcmp (progpathname, progname) == 0) + { + free (progpathname); + + /* Add the "./" prefix for real, that + concatenated_filename() optimized away. + This avoids a second PATH search when the + caller uses execl/execv/execlp/execvp. */ + progpathname = + (char *) malloc (2 + strlen (progname) + 1); + if (progpathname == NULL) + { + /* errno is set here. */ + failure_errno = errno; + free (dir_as_prefix_to_free); + goto failed; + } + progpathname[0] = '.'; + progpathname[1] = NATIVE_SLASH; + memcpy (progpathname + 2, progname, + strlen (progname) + 1); + } + + free (dir_as_prefix_to_free); + free (path_copy); + return progpathname; + } + + errno = EACCES; + } + } + + if (errno != ENOENT) + failure_errno = errno; + + free (progpathname); + } + } + #if defined _WIN32 && !defined __CYGWIN__ /* Native Windows */ + if (failure_errno == ENOENT && !progname_has_dot) + { + /* In the loop above, we skipped suffix = "". Do this loop + round now, merely to provide a better errno than ENOENT. */ + + char *progpathname = + concatenated_filename (dir_as_prefix, progname, ""); + + if (progpathname == NULL) + { + /* errno is set here. */ + failure_errno = errno; + free (dir_as_prefix_to_free); + goto failed; + } + + if (eaccess (progpathname, X_OK) == 0) + { + struct stat statbuf; + + if (stat (progpathname, &statbuf) >= 0) + { + if (! S_ISDIR (statbuf.st_mode)) + errno = ENOEXEC; + else + errno = EACCES; + } + } + + failure_errno = errno; + + free (progpathname); + } + #endif + + free (dir_as_prefix_to_free); + + if (last) + break; + } + + failed: + /* Not found in PATH. */ + free (path_copy); + + errno = failure_errno; + return NULL; + } +} |