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Diffstat (limited to 'src/unistd/exec.c')
| -rw-r--r-- | src/unistd/exec.c | 376 |
1 files changed, 376 insertions, 0 deletions
diff --git a/src/unistd/exec.c b/src/unistd/exec.c new file mode 100644 index 0000000..5c3584c --- /dev/null +++ b/src/unistd/exec.c @@ -0,0 +1,376 @@ +/** + * 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> + + + +/** + * The current environment variables. + */ +extern char** environ; + + + +/** + * Common code for the `execl*` functions. + * + * @param file The first 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 vexec(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_; + + va_copy(args, argv); + while (n++, va_arg(args, char*) != NULL) + break; + + if (fetch_envp) + envp = va_arg(args, char* const*); + + argv_ = alloca(n * sizeof(char*)); + for (i = 0; i < n; i++) + argv_[i] = va_arg(args, char*); + + (void)(use_path ? execvpe : execve)(file, argv_, envp); +} + + + +/** + * Replace the current process image with a new process image. + * + * @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. + * @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 execve(2). + */ +int execl(const char* path, ... /*, NULL */) +{ + int saved_errno; + va_list argv; + va_start(argv, path); + vexec(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. + * + * @param file The pathname of the file to execute, + * or the filename of a file in $PATH, + * 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. + * @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 execve(2). + */ +int execlp(const char* file, ... /*, NULL */) +{ + int saved_errno; + va_list argv; + va_start(argv, path); + vexec(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. + * + * @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 foramtted $name=$value. + * This list shall be `NULL`-terminated. The behaviour + * is system-dependant if this argument is `NULL`. + * @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 execve(2). + */ +int execle(const char* path, ... /*, NULL, char* const envp[] */) +{ + int saved_errno; + va_list argv; + va_start(argv, path); + vexec(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, added for completeness. + * + * @param file The pathname of the file to execute, + * or the filename of a file in $PATH, + * 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 foramtted $name=$value. + * This list shall be `NULL`-terminated. The behaviour + * is system-dependant if this argument is `NULL`. + * @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 execve(2). + */ +int execlpe(const char* file, ... /*, NULL, char* const envp[] */) +{ + int saved_errno; + va_list argv; + va_start(argv, path); + vexec(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. + * + * @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`. + * @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 execve(2). + */ +int execv(const char* path, char* const argv[]) +{ + return execve(path, argv, environ); +} + + +/** + * Replace the current process image with a new process image. + * + * @param file The pathname of the file to execute, + * or the filename of a file in $PATH, + * 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`. + * @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 execve(2). + */ +int execvp(const char* file, char* const argv[]) +{ + return execvpe(path, argv, environ); +} + + +/** + * Replace the current process image with a new process image. + * + * @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 foramtted $name=$value. + * This list shall be `NULL`-terminated. The behaviour + * is system-dependant if this argument is `NULL`. + * @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 execve(2). + */ +int execve(const char* path, char* const argv[], char* const envp[]) +{ + return errno = ENOTSUP, -1; + (void) path, (void) argv, (void) enpv; + /* TODO implement execve */ +} + + +/** + * Replace the current process image with a new process image. + * + * This is a GNU-compliant slibc extension. + * + * @param file The pathname of the file to execute, + * or the filename of a file in $PATH, + * 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 foramtted $name=$value. + * This list shall be `NULL`-terminated. The behaviour + * is system-dependant if this argument is `NULL`. + * @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 execve(2). + */ +int execvpe(const char* file, char* const argv[], char* const envp[]) +{ + char* path = NULL; + char* path_cwd = NULL; + char* path_def = NULL; + char* path_env; + char* pathname = NULL; + char* p; + char* q; + size_t len = 0; + int eacces = 0; + int saved_errno; + + if (strchr(file, '/')) + return execve(file, argv, envp); + + if (!*file) + return errno = ENOENT, -1; + + path_env = getenv(PATH); + if (path_env == NULL) + { + path_cwd = get_current_dir_name(); + if (path_cwd == NULL) + goto fail; + + len = confstr(_CS_PATH, NULL, 0); + if (len) + { + path_def = malloc((1 + len) * sizeof(char)); + if (path_def == NULL) + goto fail; + *path_def = ':'; + if (confstr(_CS_PATH, path_def + 1, len)) + path_def = NULL, len = 0; + } + if (path_def == NULL) + path_def = ":/usr/local/bin:/bin:/usr/bin"; + + path = malloc((strlen(path_cwd) + strlen(path_def) + 1) * sizeof(char)); + if (path == NULL) + goto fail; + + stpcpy(stpcpy(path, path_cwd), path_def); + free(path_cwd), path_cwd = NULL; + if (len) + free(path_def), path_def = NULL; + } + else + if (path = strdup(path_env), path == NULL) + goto fail; + + pathname = malloc((strlen(path) + strlen(file) + 2) * sizeof(char)); + + for (p = path; *p; p = q + 1) + { + q = strchr(p, ':'); + if (q == 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_cwd); + if (len) + free(path_def); + free(path); + free(pathname); + errno = saved_errno; + return -1; +} + |