1 #include <linux/compiler.h> 2 #include <linux/string.h> 3 #include <sys/types.h> 4 #include <sys/stat.h> 5 #include <unistd.h> 6 #include <string.h> 7 #include <stdlib.h> 8 #include <stdio.h> 9 #include "subcmd-util.h" 10 #include "exec-cmd.h" 11 #include "subcmd-config.h" 12 13 #define MAX_ARGS 32 14 #define PATH_MAX 4096 15 16 static const char *argv_exec_path; 17 static const char *argv0_path; 18 19 void exec_cmd_init(const char *exec_name, const char *prefix, 20 const char *exec_path, const char *exec_path_env) 21 { 22 subcmd_config.exec_name = exec_name; 23 subcmd_config.prefix = prefix; 24 subcmd_config.exec_path = exec_path; 25 subcmd_config.exec_path_env = exec_path_env; 26 } 27 28 #define is_dir_sep(c) ((c) == '/') 29 30 static int is_absolute_path(const char *path) 31 { 32 return path[0] == '/'; 33 } 34 35 static const char *get_pwd_cwd(void) 36 { 37 static char cwd[PATH_MAX + 1]; 38 char *pwd; 39 struct stat cwd_stat, pwd_stat; 40 if (getcwd(cwd, PATH_MAX) == NULL) 41 return NULL; 42 pwd = getenv("PWD"); 43 if (pwd && strcmp(pwd, cwd)) { 44 stat(cwd, &cwd_stat); 45 if (!stat(pwd, &pwd_stat) && 46 pwd_stat.st_dev == cwd_stat.st_dev && 47 pwd_stat.st_ino == cwd_stat.st_ino) { 48 strlcpy(cwd, pwd, PATH_MAX); 49 } 50 } 51 return cwd; 52 } 53 54 static const char *make_nonrelative_path(const char *path) 55 { 56 static char buf[PATH_MAX + 1]; 57 58 if (is_absolute_path(path)) { 59 if (strlcpy(buf, path, PATH_MAX) >= PATH_MAX) 60 die("Too long path: %.*s", 60, path); 61 } else { 62 const char *cwd = get_pwd_cwd(); 63 if (!cwd) 64 die("Cannot determine the current working directory"); 65 if (snprintf(buf, PATH_MAX, "%s/%s", cwd, path) >= PATH_MAX) 66 die("Too long path: %.*s", 60, path); 67 } 68 return buf; 69 } 70 71 char *system_path(const char *path) 72 { 73 char *buf = NULL; 74 75 if (is_absolute_path(path)) 76 return strdup(path); 77 78 astrcatf(&buf, "%s/%s", subcmd_config.prefix, path); 79 80 return buf; 81 } 82 83 const char *extract_argv0_path(const char *argv0) 84 { 85 const char *slash; 86 87 if (!argv0 || !*argv0) 88 return NULL; 89 slash = argv0 + strlen(argv0); 90 91 while (argv0 <= slash && !is_dir_sep(*slash)) 92 slash--; 93 94 if (slash >= argv0) { 95 argv0_path = strndup(argv0, slash - argv0); 96 return argv0_path ? slash + 1 : NULL; 97 } 98 99 return argv0; 100 } 101 102 void set_argv_exec_path(const char *exec_path) 103 { 104 argv_exec_path = exec_path; 105 /* 106 * Propagate this setting to external programs. 107 */ 108 setenv(subcmd_config.exec_path_env, exec_path, 1); 109 } 110 111 112 /* Returns the highest-priority location to look for subprograms. */ 113 char *get_argv_exec_path(void) 114 { 115 char *env; 116 117 if (argv_exec_path) 118 return strdup(argv_exec_path); 119 120 env = getenv(subcmd_config.exec_path_env); 121 if (env && *env) 122 return strdup(env); 123 124 return system_path(subcmd_config.exec_path); 125 } 126 127 static void add_path(char **out, const char *path) 128 { 129 if (path && *path) { 130 if (is_absolute_path(path)) 131 astrcat(out, path); 132 else 133 astrcat(out, make_nonrelative_path(path)); 134 135 astrcat(out, ":"); 136 } 137 } 138 139 void setup_path(void) 140 { 141 const char *old_path = getenv("PATH"); 142 char *new_path = NULL; 143 char *tmp = get_argv_exec_path(); 144 145 add_path(&new_path, tmp); 146 add_path(&new_path, argv0_path); 147 free(tmp); 148 149 if (old_path) 150 astrcat(&new_path, old_path); 151 else 152 astrcat(&new_path, "/usr/local/bin:/usr/bin:/bin"); 153 154 setenv("PATH", new_path, 1); 155 156 free(new_path); 157 } 158 159 static const char **prepare_exec_cmd(const char **argv) 160 { 161 int argc; 162 const char **nargv; 163 164 for (argc = 0; argv[argc]; argc++) 165 ; /* just counting */ 166 nargv = malloc(sizeof(*nargv) * (argc + 2)); 167 168 nargv[0] = subcmd_config.exec_name; 169 for (argc = 0; argv[argc]; argc++) 170 nargv[argc + 1] = argv[argc]; 171 nargv[argc + 1] = NULL; 172 return nargv; 173 } 174 175 int execv_cmd(const char **argv) { 176 const char **nargv = prepare_exec_cmd(argv); 177 178 /* execvp() can only ever return if it fails */ 179 execvp(subcmd_config.exec_name, (char **)nargv); 180 181 free(nargv); 182 return -1; 183 } 184 185 186 int execl_cmd(const char *cmd,...) 187 { 188 int argc; 189 const char *argv[MAX_ARGS + 1]; 190 const char *arg; 191 va_list param; 192 193 va_start(param, cmd); 194 argv[0] = cmd; 195 argc = 1; 196 while (argc < MAX_ARGS) { 197 arg = argv[argc++] = va_arg(param, char *); 198 if (!arg) 199 break; 200 } 201 va_end(param); 202 if (MAX_ARGS <= argc) { 203 fprintf(stderr, " Error: too many args to run %s\n", cmd); 204 return -1; 205 } 206 207 argv[argc] = NULL; 208 return execv_cmd(argv); 209 } 210