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Diffstat (limited to '')
| -rw-r--r-- | src/unistd/execat.c | 507 |
1 files changed, 507 insertions, 0 deletions
diff --git a/src/unistd/execat.c b/src/unistd/execat.c new file mode 100644 index 0000000..d80d24b --- /dev/null +++ b/src/unistd/execat.c @@ -0,0 +1,507 @@ +/** + * slibc — Yet another C library + * Copyright © 2015 Mattias Andrée (maandree@member.fsf.org) + * + * 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 <http://www.gnu.org/licenses/>. + */ +#include <unistd.h> +#include <stdarg.h> +#include <errno.h> +#include <alloca.h> +#include <string.h> +#include <stdlib.h> +#include <sys/types.h> +#include <sys/stat.h> + + + +/** + * The current environment variables. + */ +extern char** environ; + + + +/** + * Common code for the `execl*at` functions. + * + * @param dirfd The first argument of said functions. + * @param file The second argument of said functions. + * @param argv The rest of the arguments of said functions; + * may conclude `envp`. + * @param fetch_envp Whether `argv` includes `envp`. + * @param use_path Whether $PATH may be used. + * + * @throws Any error specified for execve(2). + */ +static void vexecat(int dirfd, const char* file, va_list argv, int fetch_envp, int use_path) +{ + char* const* envp = environ; + size_t n = 0, i; + va_list args; + char** argv_; + int flags; + + va_copy(args, argv); + while (n++, va_arg(args, char*) != NULL) + break; + + if (fetch_envp) + envp = va_arg(args, char* const*); + flags = va_arg(args, int); + + argv_ = alloca(n * sizeof(char*)); + for (i = 0; i < n; i++) + argv_[i] = va_arg(argv, char*); + + (void)(use_path ? execvpeat : execveat)(dirfd, file, argv_, envp, flags); +} + + + +/** + * Replace the current process image with a new process image. + * + * This is a slibc extension. + * + * @param dirfd File descriptor for a directory (opened with + * with the open(2) `O_PATH` flag,) that will + * act as the current working directory. + * If `AT_FDCWD`, the current working directory + * will be used. + * @param path The pathname of the file to execute. + * @param ... The arguments with which to execute the file. + * The arguments should have the type `const char*`. + * As a slibc extension, it can be empty. + * This list shall be terminated by a `NULL` sentinel. + * @param flags Bit mask that can include zero or more of the + * following flags: + * AT_EMPTY_PATH: + * If `path` is an empty string, operate on the + * file (not directory) referred to by `dirfd`. + * AT_SYMLINK_NOFOLLOW: + * If `path` is relative is a symbolic link, + * fail with `errno` set to `ELOOP`. + * @return This function does not return on success, + * on error, -1 is returned and `errno` is + * set to describe the error. + * + * @throws Any error specified for execveat(2). + */ +int execlat(int dirfd, const char* path, ... /*, NULL, int flags */) +{ + int saved_errno; + va_list argv; + va_start(argv, path); + vexecat(dirfd, path, argv, 0, 0); + saved_errno = errno; + va_end(argv); + return errno = saved_errno, -1; +} + + +/** + * Replace the current process image with a new process image. + * + * This is a slibc extension. + * + * @param dirfd File descriptor for a directory (opened with + * with the open(2) `O_PATH` flag,) that will + * act as the current working directory. + * If `AT_FDCWD`, the current working directory + * will be used. + * @param file The pathname of the file to execute, + * or the filename of a file in $PATH, + * to execute. If $PATH is not set, the current + * working directory (yes, you read that right,) + * and a default value for $PATH will be used. + * @param ... The arguments with which to execute the file. + * The arguments should have the type `const char*`. + * As a slibc extension, it can be empty. + * This list shall be terminated by a `NULL` sentinel. + * @param flags Bit mask that can include zero or more of the + * following flags: + * AT_EMPTY_PATH: + * If `file` is an empty string, operate on the + * file (not directory) referred to by `dirfd`. + * AT_SYMLINK_NOFOLLOW: + * If `file` is relative is a symbolic link, + * fail with `errno` set to `ELOOP`. + * @return This function does not return on success, + * on error, -1 is returned and `errno` is + * set to describe the error. + * + * @throws Any error specified for execveat(2). + */ +int execlpat(int dirfd, const char* file, ... /*, NULL, int flags */) +{ + int saved_errno; + va_list argv; + va_start(argv, path); + vexecat(dirfd, path, argv, 0, 1); + saved_errno = errno; + va_end(argv); + return errno = saved_errno, -1; +} + + +/** + * Replace the current process image with a new process image. + * + * This is a slibc extension. + * + * @param dirfd File descriptor for a directory (opened with + * with the open(2) `O_PATH` flag,) that will + * act as the current working directory. + * If `AT_FDCWD`, the current working directory + * will be used. + * @param path The pathname of the file to execute. + * @param ... The arguments with which to execute the file. + * The arguments should have the type `const char*`. + * As a slibc extension, it can be empty. + * This list shall be terminated by a `NULL` sentinel. + * @param envp The list of environment variables the new program shall + * have set. Each element shall be formatted $name=$value. + * This list shall be `NULL`-terminated. The behaviour + * is system-dependant if this argument is `NULL`. + * @param flags Bit mask that can include zero or more of the + * following flags: + * AT_EMPTY_PATH: + * If `path` is an empty string, operate on the + * file (not directory) referred to by `dirfd`. + * AT_SYMLINK_NOFOLLOW: + * If `path` is relative is a symbolic link, + * fail with `errno` set to `ELOOP`. + * @return This function does not return on success, + * on error, -1 is returned and `errno` is + * set to describe the error. + * + * @throws Any error specified for execveat(2). + */ +int execleat(int dirfd, const char* path, ... /*, NULL, char* const[] envp, int flags */) +{ + int saved_errno; + va_list argv; + va_start(argv, path); + vexecat(dirfd, path, argv, 1, 0); + saved_errno = errno; + va_end(argv); + return errno = saved_errno, -1; +} + + +/** + * Replace the current process image with a new process image. + * + * This is a slibc extension. + * + * @param dirfd File descriptor for a directory (opened with + * with the open(2) `O_PATH` flag,) that will + * act as the current working directory. + * If `AT_FDCWD`, the current working directory + * will be used. + * @param file The pathname of the file to execute, + * or the filename of a file in $PATH, + * to execute. If $PATH is not set, the current + * working directory (yes, you read that right,) + * and a default value for $PATH will be used. + * @param ... The arguments with which to execute the file. + * The arguments should have the type `const char*`. + * As a slibc extension, it can be empty. + * This list shall be terminated by a `NULL` sentinel. + * @param envp The list of environment variables the new program shall + * have set. Each element shall be formatted $name=$value. + * This list shall be `NULL`-terminated. The behaviour + * is system-dependant if this argument is `NULL`. + * @param flags Bit mask that can include zero or more of the + * following flags: + * AT_EMPTY_PATH: + * If `file` is an empty string, operate on the + * file (not directory) referred to by `dirfd`. + * AT_SYMLINK_NOFOLLOW: + * If `file` is relative is a symbolic link, + * fail with `errno` set to `ELOOP`. + * @return This function does not return on success, + * on error, -1 is returned and `errno` is + * set to describe the error. + * + * @throws Any error specified for execveat(2). + */ +int execlpeat(int dirfd, const char* file, ... /*, NULL, char* const[] envp, int flags */) +{ + int saved_errno; + va_list argv; + va_start(argv, path); + vexecat(dirfd, path, argv, 1, 1); + saved_errno = errno; + va_end(argv); + return errno = saved_errno, -1; +} + + +/** + * Replace the current process image with a new process image. + * + * This is a slibc extension. + * + * @param dirfd File descriptor for a directory (opened with + * with the open(2) `O_PATH` flag,) that will + * act as the current working directory. + * If `AT_FDCWD`, the current working directory + * will be used. + * @param path The pathname of the file to execute. + * @param argv The arguments with which to execute the file. + * This parameter should really have the type + * `const char* const[]`, but that probably not + * so because compiles take issue with casts + * adding const to any pointer in the type + * except the outmost pointer. This list shall + * be `NULL`-terminated. The behaviour is + * system-dependant if this argument is `NULL`. + * @param flags Bit mask that can include zero or more of the + * following flags: + * AT_EMPTY_PATH: + * If `path` is an empty string, operate on the + * file (not directory) referred to by `dirfd`. + * AT_SYMLINK_NOFOLLOW: + * If `path` is relative is a symbolic link, + * fail with `errno` set to `ELOOP`. + * @return This function does not return on success, + * on error, -1 is returned and `errno` is + * set to describe the error. + * + * @throws Any error specified for execveat(2). + */ +int execvat(int dirfd, const char* path, char* const argv[], int flags) +{ + return execveat(dirfd, path, argv, environ, flags); +} + + +/** + * Replace the current process image with a new process image. + * + * This is a slibc extension. + * + * @param dirfd File descriptor for a directory (opened with + * with the open(2) `O_PATH` flag,) that will + * act as the current working directory. + * If `AT_FDCWD`, the current working directory + * will be used. + * @param file The pathname of the file to execute, + * or the filename of a file in $PATH, + * to execute. If $PATH is not set, the current + * working directory (yes, you read that right,) + * and a default value for $PATH will be used. + * @param argv The arguments with which to execute the file. + * This parameter should really have the type + * `const char* const[]`, but that probably not + * so because compiles take issue with casts + * adding const to any pointer in the type + * except the outmost pointer. This list shall + * be `NULL`-terminated. The behaviour is + * system-dependant if this argument is `NULL`. + * @param flags Bit mask that can include zero or more of the + * following flags: + * AT_EMPTY_PATH: + * If `file` is an empty string, operate on the + * file (not directory) referred to by `dirfd`. + * AT_SYMLINK_NOFOLLOW: + * If `file` is relative is a symbolic link, + * fail with `errno` set to `ELOOP`. + * @return This function does not return on success, + * on error, -1 is returned and `errno` is + * set to describe the error. + * + * @throws Any error specified for execveat(2). + */ +int execvpat(int dirfd, const char* file, char* const argv[], int flags) +{ + return execvpe(dirfd, path, argv, environ, flags); +} + + +/** + * Replace the current process image with a new process image. + * + * @param dirfd File descriptor for a directory (opened with + * with the open(2) `O_PATH` flag,) that will + * act as the current working directory. + * If `AT_FDCWD`, the current working directory + * will be used. + * @param path The pathname of the file to execute. + * @param argv The arguments with which to execute the file. + * This parameter should really have the type + * `const char* const[]`, but that probably not + * so because compiles take issue with casts + * adding const to any pointer in the type + * except the outmost pointer. This list shall + * be `NULL`-terminated. The behaviour is + * system-dependant if this argument is `NULL`. + * @param envp The list of environment variables the new program shall + * have set. Each element shall be formatted $name=$value. + * This list shall be `NULL`-terminated. The behaviour + * is system-dependant if this argument is `NULL`. + * @param flags Bit mask that can include zero or more of the + * following flags: + * AT_EMPTY_PATH: + * If `path` is an empty string, operate on the + * file (not directory) referred to by `dirfd`. + * AT_SYMLINK_NOFOLLOW: + * If `path` is relative is a symbolic link, + * fail with `errno` set to `ELOOP`. + * @return This function does not return on success, + * on error, -1 is returned and `errno` is + * set to describe the error. + * + * @throws Any error specified for execveat(2). + */ +int execveat(int dirfd, const char* path, char* const argv[], char* const envp[], int flags) +{ +/* TODO use linux system call if available */ + struct stat attr; + char* pathname; + + if (*path == '/') + return execve(path, argv, envp); + + if ((dirfd == AT_FDCWD) && (flags & AT_EMPTY_PATH) && !*path) + return errno = EISDIR, -1; + + if ((dirfd == AT_FDCWD) && (flags & AT_SYMLINK_NOFOLLOW)) + { + if (lstat(path, &attr)) + return -1; + if (S_IFLNK(attr.st_mode)) + return errno = ELOOP, -1; + } + + pathname = malloc(sizeof("/dev/fd//") + (3 * sizeof(int) + strlen(path)) * sizeof(char)); + if (pathname == NULL) + return -1; + + sprintf(pathname, "/dev/fd/%i%s%s", dirfd, *path ? "/" : "", path); + return execve(pathname, argv, envp); +} + + +/** + * Replace the current process image with a new process image. + * + * This is a slibc extension. + * + * @param dirfd File descriptor for a directory (opened with + * with the open(2) `O_PATH` flag,) that will + * act as the current working directory. + * If `AT_FDCWD`, the current working directory + * will be used. + * @param file The pathname of the file to execute, + * or the filename of a file in $PATH, + * to execute. If $PATH is not set, the current + * working directory (yes, you read that right,) + * and a default value for $PATH will be used. + * @param argv The arguments with which to execute the file. + * This parameter should really have the type + * `const char* const[]`, but that probably not + * so because compiles take issue with casts + * adding const to any pointer in the type + * except the outmost pointer. This list shall + * be `NULL`-terminated. The behaviour is + * system-dependant if this argument is `NULL`. + * @param envp The list of environment variables the new program shall + * have set. Each element shall be formatted $name=$value. + * This list shall be `NULL`-terminated. The behaviour + * is system-dependant if this argument is `NULL`. + * @param flags Bit mask that can include zero or more of the + * following flags: + * AT_EMPTY_PATH: + * If `file` is an empty string, operate on the + * file (not directory) referred to by `dirfd`. + * AT_SYMLINK_NOFOLLOW: + * If `file` is relative is a symbolic link, + * fail with `errno` set to `ELOOP`. + * @return This function does not return on success, + * on error, -1 is returned and `errno` is + * set to describe the error. + * + * @throws Any error specified for execveat(2). + */ +int execvpeat(int dirfd, const char* file, char* const argv[], char* const envp[], int flags) +{ + char* path = NULL; + char* pathname = NULL; + char* p; + char* q; + size_t len = 0; + int eacces = 0; + int saved_errno; + + if (strchr(file, '/') || !*file) + return execveat(dirfd, file, argv, envp, flags); + + if (!*file) + return errno = ENOENT, -1; + + path = getenv(PATH); + if (path == NULL) + { + execveat(dirfd, file, argv, envp, flags); + if (errno == EACCES) eacces = 1; + else if (errno != ENOENT) goto fail; + + if ((len = confstr(_CS_PATH, NULL, 0))) + { + path = malloc(len * sizeof(char)); + if (path == NULL) + goto fail; + if (!confstr(_CS_PATH, path, len)) + free(path), path = NULL; + } + if (path == NULL) + path = strdup("/usr/local/bin:/bin:/usr/bin"); + } + else + path = strdup(path); + if (path == NULL) + goto fail; + + pathname = malloc((strlen(path) + strlen(file) + 2) * sizeof(char)); + if (pathname == NULL) + goto fail; + + for (p = path; *p; p = q + 1) + { + if (p == (q = strchr(p, ':'))) + continue; + *q = '\0'; + + stpcpy(stpcpy(stpcpy(pathname, p), "/"), file); + + execve(pathname, argv, envp); + if (errno == EACCES) eacces = 1; + else if (errno != ENOENT) goto fail; + } + + free(path); + free(pathname); + return errno = (eaccess ? EACCES : ENOENT), -1; + + fail: + saved_errno = errno; + free(path); + free(pathname); + errno = saved_errno; + return -1; +} + |