#include <linux/compiler.h> #include <linux/string.h> #include <sys/types.h> #include <sys/stat.h> #include <unistd.h> #include <string.h> #include <stdlib.h> #include <stdio.h> #include "subcmd-util.h" #include "exec-cmd.h" #include "subcmd-config.h" #define MAX_ARGS 32 #define PATH_MAX 4096 static const char *argv_exec_path; static const char *argv0_path; void exec_cmd_init(const char *exec_name, const char *prefix, const char *exec_path, const char *exec_path_env) { subcmd_config.exec_name = exec_name; subcmd_config.prefix = prefix; subcmd_config.exec_path = exec_path; subcmd_config.exec_path_env = exec_path_env; } #define is_dir_sep(c) ((c) == '/') static int is_absolute_path(const char *path) { return path[0] == '/'; } static const char *get_pwd_cwd(void) { static char cwd[PATH_MAX + 1]; char *pwd; struct stat cwd_stat, pwd_stat; if (getcwd(cwd, PATH_MAX) == NULL) return NULL; pwd = getenv("PWD"); if (pwd && strcmp(pwd, cwd)) { stat(cwd, &cwd_stat); if (!stat(pwd, &pwd_stat) && pwd_stat.st_dev == cwd_stat.st_dev && pwd_stat.st_ino == cwd_stat.st_ino) { strlcpy(cwd, pwd, PATH_MAX); } } return cwd; } static const char *make_nonrelative_path(const char *path) { static char buf[PATH_MAX + 1]; if (is_absolute_path(path)) { if (strlcpy(buf, path, PATH_MAX) >= PATH_MAX) die("Too long path: %.*s", 60, path); } else { const char *cwd = get_pwd_cwd(); if (!cwd) die("Cannot determine the current working directory"); if (snprintf(buf, PATH_MAX, "%s/%s", cwd, path) >= PATH_MAX) die("Too long path: %.*s", 60, path); } return buf; } char *system_path(const char *path) { char *buf = NULL; if (is_absolute_path(path)) return strdup(path); astrcatf(&buf, "%s/%s", subcmd_config.prefix, path); return buf; } const char *extract_argv0_path(const char *argv0) { const char *slash; if (!argv0 || !*argv0) return NULL; slash = argv0 + strlen(argv0); while (argv0 <= slash && !is_dir_sep(*slash)) slash--; if (slash >= argv0) { argv0_path = strndup(argv0, slash - argv0); return argv0_path ? slash + 1 : NULL; } return argv0; } void set_argv_exec_path(const char *exec_path) { argv_exec_path = exec_path; /* * Propagate this setting to external programs. */ setenv(subcmd_config.exec_path_env, exec_path, 1); } /* Returns the highest-priority location to look for subprograms. */ char *get_argv_exec_path(void) { char *env; if (argv_exec_path) return strdup(argv_exec_path); env = getenv(subcmd_config.exec_path_env); if (env && *env) return strdup(env); return system_path(subcmd_config.exec_path); } static void add_path(char **out, const char *path) { if (path && *path) { if (is_absolute_path(path)) astrcat(out, path); else astrcat(out, make_nonrelative_path(path)); astrcat(out, ":"); } } void setup_path(void) { const char *old_path = getenv("PATH"); char *new_path = NULL; char *tmp = get_argv_exec_path(); add_path(&new_path, tmp); add_path(&new_path, argv0_path); free(tmp); if (old_path) astrcat(&new_path, old_path); else astrcat(&new_path, "/usr/local/bin:/usr/bin:/bin"); setenv("PATH", new_path, 1); free(new_path); } static const char **prepare_exec_cmd(const char **argv) { int argc; const char **nargv; for (argc = 0; argv[argc]; argc++) ; /* just counting */ nargv = malloc(sizeof(*nargv) * (argc + 2)); nargv[0] = subcmd_config.exec_name; for (argc = 0; argv[argc]; argc++) nargv[argc + 1] = argv[argc]; nargv[argc + 1] = NULL; return nargv; } int execv_cmd(const char **argv) { const char **nargv = prepare_exec_cmd(argv); /* execvp() can only ever return if it fails */ execvp(subcmd_config.exec_name, (char **)nargv); free(nargv); return -1; } int execl_cmd(const char *cmd,...) { int argc; const char *argv[MAX_ARGS + 1]; const char *arg; va_list param; va_start(param, cmd); argv[0] = cmd; argc = 1; while (argc < MAX_ARGS) { arg = argv[argc++] = va_arg(param, char *); if (!arg) break; } va_end(param); if (MAX_ARGS <= argc) { fprintf(stderr, " Error: too many args to run %s\n", cmd); return -1; } argv[argc] = NULL; return execv_cmd(argv); }