| 1 | /* Linux-specific PROCFS manipulation routines. |
| 2 | Copyright (C) 2009-2021 Free Software Foundation, Inc. |
| 3 | |
| 4 | This file is part of GDB. |
| 5 | |
| 6 | This program is free software; you can redistribute it and/or modify |
| 7 | it under the terms of the GNU General Public License as published by |
| 8 | the Free Software Foundation; either version 3 of the License, or |
| 9 | (at your option) any later version. |
| 10 | |
| 11 | This program is distributed in the hope that it will be useful, |
| 12 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 14 | GNU General Public License for more details. |
| 15 | |
| 16 | You should have received a copy of the GNU General Public License |
| 17 | along with this program. If not, see <http://www.gnu.org/licenses/>. */ |
| 18 | |
| 19 | #include "gdbsupport/common-defs.h" |
| 20 | #include "linux-procfs.h" |
| 21 | #include "gdbsupport/filestuff.h" |
| 22 | #include <dirent.h> |
| 23 | #include <sys/stat.h> |
| 24 | |
| 25 | /* Return the TGID of LWPID from /proc/pid/status. Returns -1 if not |
| 26 | found. */ |
| 27 | |
| 28 | static int |
| 29 | linux_proc_get_int (pid_t lwpid, const char *field, int warn) |
| 30 | { |
| 31 | size_t field_len = strlen (field); |
| 32 | char buf[100]; |
| 33 | int retval = -1; |
| 34 | |
| 35 | snprintf (buf, sizeof (buf), "/proc/%d/status", (int) lwpid); |
| 36 | gdb_file_up status_file = gdb_fopen_cloexec (buf, "r"); |
| 37 | if (status_file == NULL) |
| 38 | { |
| 39 | if (warn) |
| 40 | warning (_("unable to open /proc file '%s'"), buf); |
| 41 | return -1; |
| 42 | } |
| 43 | |
| 44 | while (fgets (buf, sizeof (buf), status_file.get ())) |
| 45 | if (strncmp (buf, field, field_len) == 0 && buf[field_len] == ':') |
| 46 | { |
| 47 | retval = strtol (&buf[field_len + 1], NULL, 10); |
| 48 | break; |
| 49 | } |
| 50 | |
| 51 | return retval; |
| 52 | } |
| 53 | |
| 54 | /* Return the TGID of LWPID from /proc/pid/status. Returns -1 if not |
| 55 | found. */ |
| 56 | |
| 57 | int |
| 58 | linux_proc_get_tgid (pid_t lwpid) |
| 59 | { |
| 60 | return linux_proc_get_int (lwpid, "Tgid", 1); |
| 61 | } |
| 62 | |
| 63 | /* See linux-procfs.h. */ |
| 64 | |
| 65 | pid_t |
| 66 | linux_proc_get_tracerpid_nowarn (pid_t lwpid) |
| 67 | { |
| 68 | return linux_proc_get_int (lwpid, "TracerPid", 0); |
| 69 | } |
| 70 | |
| 71 | /* Process states as discovered in the 'State' line of |
| 72 | /proc/PID/status. Not all possible states are represented here, |
| 73 | only those that we care about. */ |
| 74 | |
| 75 | enum proc_state |
| 76 | { |
| 77 | /* Some state we don't handle. */ |
| 78 | PROC_STATE_UNKNOWN, |
| 79 | |
| 80 | /* Stopped on a signal. */ |
| 81 | PROC_STATE_STOPPED, |
| 82 | |
| 83 | /* Tracing stop. */ |
| 84 | PROC_STATE_TRACING_STOP, |
| 85 | |
| 86 | /* Dead. */ |
| 87 | PROC_STATE_DEAD, |
| 88 | |
| 89 | /* Zombie. */ |
| 90 | PROC_STATE_ZOMBIE, |
| 91 | }; |
| 92 | |
| 93 | /* Parse a PROC_STATE out of STATE, a buffer with the state found in |
| 94 | the 'State:' line of /proc/PID/status. */ |
| 95 | |
| 96 | static enum proc_state |
| 97 | parse_proc_status_state (const char *state) |
| 98 | { |
| 99 | state = skip_spaces (state); |
| 100 | |
| 101 | switch (state[0]) |
| 102 | { |
| 103 | case 't': |
| 104 | return PROC_STATE_TRACING_STOP; |
| 105 | case 'T': |
| 106 | /* Before Linux 2.6.33, tracing stop used uppercase T. */ |
| 107 | if (strcmp (state, "T (stopped)\n") == 0) |
| 108 | return PROC_STATE_STOPPED; |
| 109 | else /* "T (tracing stop)\n" */ |
| 110 | return PROC_STATE_TRACING_STOP; |
| 111 | case 'X': |
| 112 | return PROC_STATE_DEAD; |
| 113 | case 'Z': |
| 114 | return PROC_STATE_ZOMBIE; |
| 115 | } |
| 116 | |
| 117 | return PROC_STATE_UNKNOWN; |
| 118 | } |
| 119 | |
| 120 | |
| 121 | /* Fill in STATE, a buffer with BUFFER_SIZE bytes with the 'State' |
| 122 | line of /proc/PID/status. Returns -1 on failure to open the /proc |
| 123 | file, 1 if the line is found, and 0 if not found. If WARN, warn on |
| 124 | failure to open the /proc file. */ |
| 125 | |
| 126 | static int |
| 127 | linux_proc_pid_get_state (pid_t pid, int warn, enum proc_state *state) |
| 128 | { |
| 129 | int have_state; |
| 130 | char buffer[100]; |
| 131 | |
| 132 | xsnprintf (buffer, sizeof (buffer), "/proc/%d/status", (int) pid); |
| 133 | gdb_file_up procfile = gdb_fopen_cloexec (buffer, "r"); |
| 134 | if (procfile == NULL) |
| 135 | { |
| 136 | if (warn) |
| 137 | warning (_("unable to open /proc file '%s'"), buffer); |
| 138 | return -1; |
| 139 | } |
| 140 | |
| 141 | have_state = 0; |
| 142 | while (fgets (buffer, sizeof (buffer), procfile.get ()) != NULL) |
| 143 | if (startswith (buffer, "State:")) |
| 144 | { |
| 145 | have_state = 1; |
| 146 | *state = parse_proc_status_state (buffer + sizeof ("State:") - 1); |
| 147 | break; |
| 148 | } |
| 149 | return have_state; |
| 150 | } |
| 151 | |
| 152 | /* See linux-procfs.h declaration. */ |
| 153 | |
| 154 | int |
| 155 | linux_proc_pid_is_gone (pid_t pid) |
| 156 | { |
| 157 | int have_state; |
| 158 | enum proc_state state; |
| 159 | |
| 160 | have_state = linux_proc_pid_get_state (pid, 0, &state); |
| 161 | if (have_state < 0) |
| 162 | { |
| 163 | /* If we can't open the status file, assume the thread has |
| 164 | disappeared. */ |
| 165 | return 1; |
| 166 | } |
| 167 | else if (have_state == 0) |
| 168 | { |
| 169 | /* No "State:" line, assume thread is alive. */ |
| 170 | return 0; |
| 171 | } |
| 172 | else |
| 173 | return (state == PROC_STATE_ZOMBIE || state == PROC_STATE_DEAD); |
| 174 | } |
| 175 | |
| 176 | /* Return non-zero if 'State' of /proc/PID/status contains STATE. If |
| 177 | WARN, warn on failure to open the /proc file. */ |
| 178 | |
| 179 | static int |
| 180 | linux_proc_pid_has_state (pid_t pid, enum proc_state state, int warn) |
| 181 | { |
| 182 | int have_state; |
| 183 | enum proc_state cur_state; |
| 184 | |
| 185 | have_state = linux_proc_pid_get_state (pid, warn, &cur_state); |
| 186 | return (have_state > 0 && cur_state == state); |
| 187 | } |
| 188 | |
| 189 | /* Detect `T (stopped)' in `/proc/PID/status'. |
| 190 | Other states including `T (tracing stop)' are reported as false. */ |
| 191 | |
| 192 | int |
| 193 | linux_proc_pid_is_stopped (pid_t pid) |
| 194 | { |
| 195 | return linux_proc_pid_has_state (pid, PROC_STATE_STOPPED, 1); |
| 196 | } |
| 197 | |
| 198 | /* Detect `t (tracing stop)' in `/proc/PID/status'. |
| 199 | Other states including `T (stopped)' are reported as false. */ |
| 200 | |
| 201 | int |
| 202 | linux_proc_pid_is_trace_stopped_nowarn (pid_t pid) |
| 203 | { |
| 204 | return linux_proc_pid_has_state (pid, PROC_STATE_TRACING_STOP, 1); |
| 205 | } |
| 206 | |
| 207 | /* Return non-zero if PID is a zombie. If WARN, warn on failure to |
| 208 | open the /proc file. */ |
| 209 | |
| 210 | static int |
| 211 | linux_proc_pid_is_zombie_maybe_warn (pid_t pid, int warn) |
| 212 | { |
| 213 | return linux_proc_pid_has_state (pid, PROC_STATE_ZOMBIE, warn); |
| 214 | } |
| 215 | |
| 216 | /* See linux-procfs.h declaration. */ |
| 217 | |
| 218 | int |
| 219 | linux_proc_pid_is_zombie_nowarn (pid_t pid) |
| 220 | { |
| 221 | return linux_proc_pid_is_zombie_maybe_warn (pid, 0); |
| 222 | } |
| 223 | |
| 224 | /* See linux-procfs.h declaration. */ |
| 225 | |
| 226 | int |
| 227 | linux_proc_pid_is_zombie (pid_t pid) |
| 228 | { |
| 229 | return linux_proc_pid_is_zombie_maybe_warn (pid, 1); |
| 230 | } |
| 231 | |
| 232 | /* See linux-procfs.h. */ |
| 233 | |
| 234 | const char * |
| 235 | linux_proc_tid_get_name (ptid_t ptid) |
| 236 | { |
| 237 | #define TASK_COMM_LEN 16 /* As defined in the kernel's sched.h. */ |
| 238 | |
| 239 | static char comm_buf[TASK_COMM_LEN]; |
| 240 | char comm_path[100]; |
| 241 | const char *comm_val; |
| 242 | pid_t pid = ptid.pid (); |
| 243 | pid_t tid = ptid.lwp_p () ? ptid.lwp () : ptid.pid (); |
| 244 | |
| 245 | xsnprintf (comm_path, sizeof (comm_path), |
| 246 | "/proc/%ld/task/%ld/comm", (long) pid, (long) tid); |
| 247 | |
| 248 | gdb_file_up comm_file = gdb_fopen_cloexec (comm_path, "r"); |
| 249 | if (comm_file == NULL) |
| 250 | return NULL; |
| 251 | |
| 252 | comm_val = fgets (comm_buf, sizeof (comm_buf), comm_file.get ()); |
| 253 | |
| 254 | if (comm_val != NULL) |
| 255 | { |
| 256 | int i; |
| 257 | |
| 258 | /* Make sure there is no newline at the end. */ |
| 259 | for (i = 0; i < sizeof (comm_buf); i++) |
| 260 | { |
| 261 | if (comm_buf[i] == '\n') |
| 262 | { |
| 263 | comm_buf[i] = '\0'; |
| 264 | break; |
| 265 | } |
| 266 | } |
| 267 | } |
| 268 | |
| 269 | return comm_val; |
| 270 | } |
| 271 | |
| 272 | /* See linux-procfs.h. */ |
| 273 | |
| 274 | void |
| 275 | linux_proc_attach_tgid_threads (pid_t pid, |
| 276 | linux_proc_attach_lwp_func attach_lwp) |
| 277 | { |
| 278 | DIR *dir; |
| 279 | char pathname[128]; |
| 280 | int new_threads_found; |
| 281 | int iterations; |
| 282 | |
| 283 | if (linux_proc_get_tgid (pid) != pid) |
| 284 | return; |
| 285 | |
| 286 | xsnprintf (pathname, sizeof (pathname), "/proc/%ld/task", (long) pid); |
| 287 | dir = opendir (pathname); |
| 288 | if (dir == NULL) |
| 289 | { |
| 290 | warning (_("Could not open /proc/%ld/task."), (long) pid); |
| 291 | return; |
| 292 | } |
| 293 | |
| 294 | /* Scan the task list for existing threads. While we go through the |
| 295 | threads, new threads may be spawned. Cycle through the list of |
| 296 | threads until we have done two iterations without finding new |
| 297 | threads. */ |
| 298 | for (iterations = 0; iterations < 2; iterations++) |
| 299 | { |
| 300 | struct dirent *dp; |
| 301 | |
| 302 | new_threads_found = 0; |
| 303 | while ((dp = readdir (dir)) != NULL) |
| 304 | { |
| 305 | unsigned long lwp; |
| 306 | |
| 307 | /* Fetch one lwp. */ |
| 308 | lwp = strtoul (dp->d_name, NULL, 10); |
| 309 | if (lwp != 0) |
| 310 | { |
| 311 | ptid_t ptid = ptid_t (pid, lwp, 0); |
| 312 | |
| 313 | if (attach_lwp (ptid)) |
| 314 | new_threads_found = 1; |
| 315 | } |
| 316 | } |
| 317 | |
| 318 | if (new_threads_found) |
| 319 | { |
| 320 | /* Start over. */ |
| 321 | iterations = -1; |
| 322 | } |
| 323 | |
| 324 | rewinddir (dir); |
| 325 | } |
| 326 | |
| 327 | closedir (dir); |
| 328 | } |
| 329 | |
| 330 | /* See linux-procfs.h. */ |
| 331 | |
| 332 | int |
| 333 | linux_proc_task_list_dir_exists (pid_t pid) |
| 334 | { |
| 335 | char pathname[128]; |
| 336 | struct stat buf; |
| 337 | |
| 338 | xsnprintf (pathname, sizeof (pathname), "/proc/%ld/task", (long) pid); |
| 339 | return (stat (pathname, &buf) == 0); |
| 340 | } |
| 341 | |
| 342 | /* See linux-procfs.h. */ |
| 343 | |
| 344 | char * |
| 345 | linux_proc_pid_to_exec_file (int pid) |
| 346 | { |
| 347 | static char buf[PATH_MAX]; |
| 348 | char name[PATH_MAX]; |
| 349 | ssize_t len; |
| 350 | |
| 351 | xsnprintf (name, PATH_MAX, "/proc/%d/exe", pid); |
| 352 | len = readlink (name, buf, PATH_MAX - 1); |
| 353 | if (len <= 0) |
| 354 | strcpy (buf, name); |
| 355 | else |
| 356 | buf[len] = '\0'; |
| 357 | |
| 358 | return buf; |
| 359 | } |
| 360 | |
| 361 | /* See linux-procfs.h. */ |
| 362 | |
| 363 | void |
| 364 | linux_proc_init_warnings () |
| 365 | { |
| 366 | static bool warned = false; |
| 367 | |
| 368 | if (warned) |
| 369 | return; |
| 370 | warned = true; |
| 371 | |
| 372 | struct stat st; |
| 373 | |
| 374 | if (stat ("/proc/self", &st) != 0) |
| 375 | warning (_("/proc is not accessible.")); |
| 376 | } |