diff options
Diffstat (limited to 'src/exec.c')
-rw-r--r-- | src/exec.c | 715 |
1 files changed, 715 insertions, 0 deletions
diff --git a/src/exec.c b/src/exec.c new file mode 100644 index 0000000..0130317 --- /dev/null +++ b/src/exec.c @@ -0,0 +1,715 @@ +/**************************************************************************** + * bfs * + * Copyright (C) 2017-2022 Tavian Barnes <tavianator@tavianator.com> * + * * + * Permission to use, copy, modify, and/or distribute this software for any * + * purpose with or without fee is hereby granted. * + * * + * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES * + * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF * + * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR * + * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES * + * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN * + * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF * + * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. * + ****************************************************************************/ + +#include "exec.h" +#include "bftw.h" +#include "ctx.h" +#include "color.h" +#include "diag.h" +#include "dstring.h" +#include "util.h" +#include "xspawn.h" +#include <assert.h> +#include <errno.h> +#include <fcntl.h> +#include <stdarg.h> +#include <stdbool.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <sys/resource.h> +#include <sys/wait.h> +#include <unistd.h> + +/** Print some debugging info. */ +BFS_FORMATTER(2, 3) +static void bfs_exec_debug(const struct bfs_exec *execbuf, const char *format, ...) { + const struct bfs_ctx *ctx = execbuf->ctx; + + if (!bfs_debug(ctx, DEBUG_EXEC, "${blu}")) { + return; + } + + if (execbuf->flags & BFS_EXEC_CONFIRM) { + fputs("-ok", stderr); + } else { + fputs("-exec", stderr); + } + if (execbuf->flags & BFS_EXEC_CHDIR) { + fputs("dir", stderr); + } + cfprintf(ctx->cerr, "${rs}: "); + + va_list args; + va_start(args, format); + vfprintf(stderr, format, args); + va_end(args); +} + +/** Determine the size of a single argument, for comparison to arg_max. */ +static size_t bfs_exec_arg_size(const char *arg) { + return sizeof(arg) + strlen(arg) + 1; +} + +/** Even if we can pass a bigger argument list, cap it here. */ +#define BFS_EXEC_ARG_MAX (16 << 20) + +/** Determine the maximum argv size. */ +static size_t bfs_exec_arg_max(const struct bfs_exec *execbuf) { + long arg_max = sysconf(_SC_ARG_MAX); + bfs_exec_debug(execbuf, "ARG_MAX: %ld according to sysconf()\n", arg_max); + if (arg_max < 0) { + arg_max = BFS_EXEC_ARG_MAX; + bfs_exec_debug(execbuf, "ARG_MAX: %ld assumed\n", arg_max); + } + + // We have to share space with the environment variables + extern char **environ; + for (char **envp = environ; *envp; ++envp) { + arg_max -= bfs_exec_arg_size(*envp); + } + // Account for the terminating NULL entry + arg_max -= sizeof(char *); + bfs_exec_debug(execbuf, "ARG_MAX: %ld remaining after environment variables\n", arg_max); + + // Account for the fixed arguments + for (size_t i = 0; i < execbuf->tmpl_argc - 1; ++i) { + arg_max -= bfs_exec_arg_size(execbuf->tmpl_argv[i]); + } + // Account for the terminating NULL entry + arg_max -= sizeof(char *); + bfs_exec_debug(execbuf, "ARG_MAX: %ld remaining after fixed arguments\n", arg_max); + + // Assume arguments are counted with the granularity of a single page, + // so allow a one page cushion to account for rounding up + long page_size = sysconf(_SC_PAGESIZE); + if (page_size < 4096) { + page_size = 4096; + } + arg_max -= page_size; + bfs_exec_debug(execbuf, "ARG_MAX: %ld remaining after page cushion\n", arg_max); + + // POSIX recommends an additional 2048 bytes of headroom + arg_max -= 2048; + bfs_exec_debug(execbuf, "ARG_MAX: %ld remaining after headroom\n", arg_max); + + if (arg_max < 0) { + arg_max = 0; + } else if (arg_max > BFS_EXEC_ARG_MAX) { + arg_max = BFS_EXEC_ARG_MAX; + } + + bfs_exec_debug(execbuf, "ARG_MAX: %ld final value\n", arg_max); + return arg_max; +} + +/** Highlight part of the command line as an error. */ +static void bfs_exec_parse_error(const struct bfs_ctx *ctx, const struct bfs_exec *execbuf) { + char **argv = execbuf->tmpl_argv - 1; + size_t argc = execbuf->tmpl_argc + 1; + if (argv[argc]) { + ++argc; + } + + bool args[ctx->argc]; + for (size_t i = 0; i < ctx->argc; ++i) { + args[i] = false; + } + + size_t i = argv - ctx->argv; + for (size_t j = 0; j < argc; ++j) { + args[i + j] = true; + } + + bfs_argv_error(ctx, args); +} + +struct bfs_exec *bfs_exec_parse(const struct bfs_ctx *ctx, char **argv, enum bfs_exec_flags flags) { + struct bfs_exec *execbuf = malloc(sizeof(*execbuf)); + if (!execbuf) { + bfs_perror(ctx, "malloc()"); + goto fail; + } + + execbuf->flags = flags; + execbuf->ctx = ctx; + execbuf->tmpl_argv = argv + 1; + execbuf->tmpl_argc = 0; + execbuf->argv = NULL; + execbuf->argc = 0; + execbuf->argv_cap = 0; + execbuf->arg_size = 0; + execbuf->arg_max = 0; + execbuf->arg_min = 0; + execbuf->wd_fd = -1; + execbuf->wd_path = NULL; + execbuf->wd_len = 0; + execbuf->ret = 0; + + while (true) { + const char *arg = execbuf->tmpl_argv[execbuf->tmpl_argc]; + if (!arg) { + if (execbuf->flags & BFS_EXEC_CONFIRM) { + bfs_exec_parse_error(ctx, execbuf); + bfs_error(ctx, "Expected '... ;'.\n"); + } else { + bfs_exec_parse_error(ctx, execbuf); + bfs_error(ctx, "Expected '... ;' or '... {} +'.\n"); + } + goto fail; + } else if (strcmp(arg, ";") == 0) { + break; + } else if (strcmp(arg, "+") == 0) { + const char *prev = execbuf->tmpl_argv[execbuf->tmpl_argc - 1]; + if (!(execbuf->flags & BFS_EXEC_CONFIRM) && strcmp(prev, "{}") == 0) { + execbuf->flags |= BFS_EXEC_MULTI; + break; + } + } + + ++execbuf->tmpl_argc; + } + + if (execbuf->tmpl_argc == 0) { + bfs_exec_parse_error(ctx, execbuf); + bfs_error(ctx, "Missing command.\n"); + goto fail; + } + + execbuf->argv_cap = execbuf->tmpl_argc + 1; + execbuf->argv = malloc(execbuf->argv_cap*sizeof(*execbuf->argv)); + if (!execbuf->argv) { + bfs_perror(ctx, "malloc()"); + goto fail; + } + + if (execbuf->flags & BFS_EXEC_MULTI) { + for (size_t i = 0; i < execbuf->tmpl_argc - 1; ++i) { + char *arg = execbuf->tmpl_argv[i]; + if (strstr(arg, "{}")) { + bfs_exec_parse_error(ctx, execbuf); + bfs_error(ctx, "Only one '{}' is supported.\n"); + goto fail; + } + execbuf->argv[i] = arg; + } + execbuf->argc = execbuf->tmpl_argc - 1; + + execbuf->arg_max = bfs_exec_arg_max(execbuf); + execbuf->arg_min = execbuf->arg_max; + } + + return execbuf; + +fail: + bfs_exec_free(execbuf); + return NULL; +} + +/** Format the current path for use as a command line argument. */ +static char *bfs_exec_format_path(const struct bfs_exec *execbuf, const struct BFTW *ftwbuf) { + if (!(execbuf->flags & BFS_EXEC_CHDIR)) { + return strdup(ftwbuf->path); + } + + const char *name = ftwbuf->path + ftwbuf->nameoff; + + if (name[0] == '/') { + // Must be a root path ("/", "//", etc.) + return strdup(name); + } + + // For compatibility with GNU find, use './name' instead of just 'name' + char *path = malloc(2 + strlen(name) + 1); + if (!path) { + return NULL; + } + + strcpy(path, "./"); + strcpy(path + 2, name); + + return path; +} + +/** Format an argument, expanding "{}" to the current path. */ +static char *bfs_exec_format_arg(char *arg, const char *path) { + char *match = strstr(arg, "{}"); + if (!match) { + return arg; + } + + char *ret = dstralloc(0); + if (!ret) { + return NULL; + } + + char *last = arg; + do { + if (dstrncat(&ret, last, match - last) != 0) { + goto err; + } + if (dstrcat(&ret, path) != 0) { + goto err; + } + + last = match + 2; + match = strstr(last, "{}"); + } while (match); + + if (dstrcat(&ret, last) != 0) { + goto err; + } + + return ret; + +err: + dstrfree(ret); + return NULL; +} + +/** Free a formatted argument. */ +static void bfs_exec_free_arg(char *arg, const char *tmpl) { + if (arg != tmpl) { + dstrfree(arg); + } +} + +/** Open a file to use as the working directory. */ +static int bfs_exec_openwd(struct bfs_exec *execbuf, const struct BFTW *ftwbuf) { + assert(execbuf->wd_fd < 0); + assert(!execbuf->wd_path); + + if (ftwbuf->at_fd != AT_FDCWD) { + // Rely on at_fd being the immediate parent + assert(ftwbuf->at_path == xbasename(ftwbuf->at_path)); + + execbuf->wd_fd = ftwbuf->at_fd; + if (!(execbuf->flags & BFS_EXEC_MULTI)) { + return 0; + } + + execbuf->wd_fd = dup_cloexec(execbuf->wd_fd); + if (execbuf->wd_fd < 0) { + return -1; + } + } + + execbuf->wd_len = ftwbuf->nameoff; + if (execbuf->wd_len == 0) { + if (ftwbuf->path[0] == '/') { + ++execbuf->wd_len; + } else { + // The path is something like "foo", so we're already in the right directory + return 0; + } + } + + execbuf->wd_path = strndup(ftwbuf->path, execbuf->wd_len); + if (!execbuf->wd_path) { + return -1; + } + + if (execbuf->wd_fd < 0) { + execbuf->wd_fd = open(execbuf->wd_path, O_RDONLY | O_CLOEXEC | O_DIRECTORY); + } + + if (execbuf->wd_fd < 0) { + return -1; + } + + return 0; +} + +/** Close the working directory. */ +static void bfs_exec_closewd(struct bfs_exec *execbuf, const struct BFTW *ftwbuf) { + if (execbuf->wd_fd >= 0) { + if (!ftwbuf || execbuf->wd_fd != ftwbuf->at_fd) { + xclose(execbuf->wd_fd); + } + execbuf->wd_fd = -1; + } + + if (execbuf->wd_path) { + free(execbuf->wd_path); + execbuf->wd_path = NULL; + execbuf->wd_len = 0; + } +} + +/** Actually spawn the process. */ +static int bfs_exec_spawn(const struct bfs_exec *execbuf) { + if (execbuf->flags & BFS_EXEC_CONFIRM) { + for (size_t i = 0; i < execbuf->argc; ++i) { + if (fprintf(stderr, "%s ", execbuf->argv[i]) < 0) { + return -1; + } + } + if (fprintf(stderr, "? ") < 0) { + return -1; + } + + if (ynprompt() <= 0) { + errno = 0; + return -1; + } + } + + // Flush cached state for consistency with the external process + bfs_ctx_flush(execbuf->ctx); + + if (execbuf->flags & BFS_EXEC_MULTI) { + bfs_exec_debug(execbuf, "Executing '%s' ... [%zu arguments] (size %zu)\n", + execbuf->argv[0], execbuf->argc - 1, execbuf->arg_size); + } else { + bfs_exec_debug(execbuf, "Executing '%s' ... [%zu arguments]\n", execbuf->argv[0], execbuf->argc - 1); + } + + pid_t pid = -1; + int error; + + struct bfs_spawn ctx; + if (bfs_spawn_init(&ctx) != 0) { + return -1; + } + + if (bfs_spawn_setflags(&ctx, BFS_SPAWN_USEPATH) != 0) { + goto fail; + } + + // Reset RLIMIT_NOFILE, to avoid breaking applications that use select() + struct rlimit rl = { + .rlim_cur = execbuf->ctx->nofile_soft, + .rlim_max = execbuf->ctx->nofile_hard, + }; + if (bfs_spawn_addsetrlimit(&ctx, RLIMIT_NOFILE, &rl) != 0) { + goto fail; + } + + if (execbuf->wd_fd >= 0) { + if (bfs_spawn_addfchdir(&ctx, execbuf->wd_fd) != 0) { + goto fail; + } + } + + pid = bfs_spawn(execbuf->argv[0], &ctx, execbuf->argv, NULL); +fail: + error = errno; + bfs_spawn_destroy(&ctx); + if (pid < 0) { + errno = error; + return -1; + } + + int wstatus; + if (waitpid(pid, &wstatus, 0) < 0) { + return -1; + } + + int ret = -1; + + if (WIFEXITED(wstatus)) { + int status = WEXITSTATUS(wstatus); + if (status == EXIT_SUCCESS) { + ret = 0; + } else { + bfs_exec_debug(execbuf, "Command '%s' failed with status %d\n", execbuf->argv[0], status); + } + } else if (WIFSIGNALED(wstatus)) { + int sig = WTERMSIG(wstatus); + const char *str = strsignal(sig); + if (!str) { + str = "unknown"; + } + bfs_warning(execbuf->ctx, "Command '${ex}%s${rs}' terminated by signal %d (%s)\n", execbuf->argv[0], sig, str); + } else { + bfs_warning(execbuf->ctx, "Command '${ex}%s${rs}' terminated abnormally\n", execbuf->argv[0]); + } + + errno = 0; + return ret; +} + +/** exec() a command for a single file. */ +static int bfs_exec_single(struct bfs_exec *execbuf, const struct BFTW *ftwbuf) { + int ret = -1, error = 0; + + char *path = bfs_exec_format_path(execbuf, ftwbuf); + if (!path) { + goto out; + } + + size_t i; + for (i = 0; i < execbuf->tmpl_argc; ++i) { + execbuf->argv[i] = bfs_exec_format_arg(execbuf->tmpl_argv[i], path); + if (!execbuf->argv[i]) { + goto out_free; + } + } + execbuf->argv[i] = NULL; + execbuf->argc = i; + + if (execbuf->flags & BFS_EXEC_CHDIR) { + if (bfs_exec_openwd(execbuf, ftwbuf) != 0) { + goto out_free; + } + } + + ret = bfs_exec_spawn(execbuf); + +out_free: + error = errno; + + bfs_exec_closewd(execbuf, ftwbuf); + + for (size_t j = 0; j < i; ++j) { + bfs_exec_free_arg(execbuf->argv[j], execbuf->tmpl_argv[j]); + } + + free(path); + + errno = error; + +out: + return ret; +} + +/** Check if any arguments remain in the buffer. */ +static bool bfs_exec_args_remain(const struct bfs_exec *execbuf) { + return execbuf->argc >= execbuf->tmpl_argc; +} + +/** Compute the current ARG_MAX estimate for binary search. */ +static size_t bfs_exec_estimate_max(const struct bfs_exec *execbuf) { + size_t min = execbuf->arg_min; + size_t max = execbuf->arg_max; + return min + (max - min)/2; +} + +/** Update the ARG_MAX lower bound from a successful execution. */ +static void bfs_exec_update_min(struct bfs_exec *execbuf) { + if (execbuf->arg_size > execbuf->arg_min) { + execbuf->arg_min = execbuf->arg_size; + + // Don't let min exceed max + if (execbuf->arg_min > execbuf->arg_max) { + execbuf->arg_min = execbuf->arg_max; + } + + size_t estimate = bfs_exec_estimate_max(execbuf); + bfs_exec_debug(execbuf, "ARG_MAX between [%zu, %zu], trying %zu\n", + execbuf->arg_min, execbuf->arg_max, estimate); + } +} + +/** Update the ARG_MAX upper bound from a failed execution. */ +static size_t bfs_exec_update_max(struct bfs_exec *execbuf) { + bfs_exec_debug(execbuf, "Got E2BIG, shrinking argument list...\n"); + + size_t size = execbuf->arg_size; + if (size <= execbuf->arg_min) { + // Lower bound was wrong, restart binary search. + execbuf->arg_min = 0; + } + + // Trim a fraction off the max size to avoid repeated failures near the + // top end of the working range + size -= size/16; + if (size < execbuf->arg_max) { + execbuf->arg_max = size; + + // Don't let min exceed max + if (execbuf->arg_min > execbuf->arg_max) { + execbuf->arg_min = execbuf->arg_max; + } + } + + // Binary search for a more precise bound + size_t estimate = bfs_exec_estimate_max(execbuf); + bfs_exec_debug(execbuf, "ARG_MAX between [%zu, %zu], trying %zu\n", + execbuf->arg_min, execbuf->arg_max, estimate); + return estimate; +} + +/** Execute the pending command from a BFS_EXEC_MULTI execbuf. */ +static int bfs_exec_flush(struct bfs_exec *execbuf) { + int ret = 0, error = 0; + + size_t orig_argc = execbuf->argc; + while (bfs_exec_args_remain(execbuf)) { + execbuf->argv[execbuf->argc] = NULL; + ret = bfs_exec_spawn(execbuf); + error = errno; + if (ret == 0) { + bfs_exec_update_min(execbuf); + break; + } else if (error != E2BIG) { + break; + } + + // Try to recover from E2BIG by trying fewer and fewer arguments + // until they fit + size_t new_max = bfs_exec_update_max(execbuf); + while (execbuf->arg_size > new_max) { + execbuf->argv[execbuf->argc] = execbuf->argv[execbuf->argc - 1]; + execbuf->arg_size -= bfs_exec_arg_size(execbuf->argv[execbuf->argc]); + --execbuf->argc; + } + } + + size_t new_argc = execbuf->argc; + for (size_t i = execbuf->tmpl_argc - 1; i < new_argc; ++i) { + free(execbuf->argv[i]); + } + execbuf->argc = execbuf->tmpl_argc - 1; + execbuf->arg_size = 0; + + if (new_argc < orig_argc) { + // If we recovered from E2BIG, there are unused arguments at the + // end of the list + for (size_t i = new_argc + 1; i <= orig_argc; ++i) { + if (error == 0) { + execbuf->argv[execbuf->argc] = execbuf->argv[i]; + execbuf->arg_size += bfs_exec_arg_size(execbuf->argv[execbuf->argc]); + ++execbuf->argc; + } else { + free(execbuf->argv[i]); + } + } + } + + errno = error; + return ret; +} + +/** Check if we need to flush the execbuf because we're changing directories. */ +static bool bfs_exec_changed_dirs(const struct bfs_exec *execbuf, const struct BFTW *ftwbuf) { + if (execbuf->flags & BFS_EXEC_CHDIR) { + if (ftwbuf->nameoff > execbuf->wd_len + || (execbuf->wd_path && strncmp(ftwbuf->path, execbuf->wd_path, execbuf->wd_len) != 0)) { + bfs_exec_debug(execbuf, "Changed directories, executing buffered command\n"); + return true; + } + } + + return false; +} + +/** Check if we need to flush the execbuf because we're too big. */ +static bool bfs_exec_would_overflow(const struct bfs_exec *execbuf, const char *arg) { + size_t arg_max = bfs_exec_estimate_max(execbuf); + size_t next_size = execbuf->arg_size + bfs_exec_arg_size(arg); + if (next_size > arg_max) { + bfs_exec_debug(execbuf, "Command size (%zu) would exceed maximum (%zu), executing buffered command\n", + next_size, arg_max); + return true; + } + + return false; +} + +/** Push a new argument to a BFS_EXEC_MULTI execbuf. */ +static int bfs_exec_push(struct bfs_exec *execbuf, char *arg) { + execbuf->argv[execbuf->argc] = arg; + + if (execbuf->argc + 1 >= execbuf->argv_cap) { + size_t cap = 2*execbuf->argv_cap; + char **argv = realloc(execbuf->argv, cap*sizeof(*argv)); + if (!argv) { + return -1; + } + execbuf->argv = argv; + execbuf->argv_cap = cap; + } + + ++execbuf->argc; + execbuf->arg_size += bfs_exec_arg_size(arg); + return 0; +} + +/** Handle a new path for a BFS_EXEC_MULTI execbuf. */ +static int bfs_exec_multi(struct bfs_exec *execbuf, const struct BFTW *ftwbuf) { + int ret = 0; + + char *arg = bfs_exec_format_path(execbuf, ftwbuf); + if (!arg) { + ret = -1; + goto out; + } + + if (bfs_exec_changed_dirs(execbuf, ftwbuf)) { + while (bfs_exec_args_remain(execbuf)) { + ret |= bfs_exec_flush(execbuf); + } + bfs_exec_closewd(execbuf, ftwbuf); + } else if (bfs_exec_would_overflow(execbuf, arg)) { + ret |= bfs_exec_flush(execbuf); + } + + if ((execbuf->flags & BFS_EXEC_CHDIR) && execbuf->wd_fd < 0) { + if (bfs_exec_openwd(execbuf, ftwbuf) != 0) { + ret = -1; + goto out_arg; + } + } + + if (bfs_exec_push(execbuf, arg) != 0) { + ret = -1; + goto out_arg; + } + + // arg will get cleaned up later by bfs_exec_flush() + goto out; + +out_arg: + free(arg); +out: + return ret; +} + +int bfs_exec(struct bfs_exec *execbuf, const struct BFTW *ftwbuf) { + if (execbuf->flags & BFS_EXEC_MULTI) { + if (bfs_exec_multi(execbuf, ftwbuf) == 0) { + errno = 0; + } else { + execbuf->ret = -1; + } + // -exec ... + never returns false + return 0; + } else { + return bfs_exec_single(execbuf, ftwbuf); + } +} + +int bfs_exec_finish(struct bfs_exec *execbuf) { + if (execbuf->flags & BFS_EXEC_MULTI) { + bfs_exec_debug(execbuf, "Finishing execution, executing buffered command\n"); + while (bfs_exec_args_remain(execbuf)) { + execbuf->ret |= bfs_exec_flush(execbuf); + } + if (execbuf->ret != 0) { + bfs_exec_debug(execbuf, "One or more executions of '%s' failed\n", execbuf->argv[0]); + } + } + return execbuf->ret; +} + +void bfs_exec_free(struct bfs_exec *execbuf) { + if (execbuf) { + bfs_exec_closewd(execbuf, NULL); + free(execbuf->argv); + free(execbuf); + } +} |