spawn: New posix_spawn()-like API for exec

6 files changed, 243 insertions, 85 deletions

diff --git a/Makefile b/Makefile
index cb6a4a0..fcab96f 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,6 @@
 ############################################################################
 # bfs                                                                      #
-# Copyright (C) 2015-2017 Tavian Barnes <tavianator@tavianator.com>        #
+# Copyright (C) 2015-2018 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.                           #
@@ -51,7 +51,7 @@ ALL_LDFLAGS = $(ALL_CFLAGS) $(LDFLAGS)
 
 all: bfs
 
-bfs: bftw.o color.o dstring.o eval.o exec.o main.o mtab.o opt.o parse.o printf.o stat.o typo.o util.o
+bfs: bftw.o color.o dstring.o eval.o exec.o main.o mtab.o opt.o parse.o printf.o spawn.o stat.o typo.o util.o
 	$(CC) $(ALL_LDFLAGS) $^ -o $@
 
 sanitized: CFLAGS := -g $(WFLAGS) -fsanitize=address -fsanitize=undefined
diff --git a/exec.c b/exec.c
index 3cb05f4..c2163e3 100644
--- a/exec.c
+++ b/exec.c
@@ -1,6 +1,6 @@
 /****************************************************************************
  * bfs                                                                      *
- * Copyright (C) 2017 Tavian Barnes <tavianator@tavianator.com>             *
+ * Copyright (C) 2017-2018 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.                           *
@@ -19,6 +19,7 @@
 #include "cmdline.h"
 #include "color.h"
 #include "dstring.h"
+#include "spawn.h"
 #include "util.h"
 #include <assert.h>
 #include <errno.h>
@@ -339,75 +340,56 @@ static int bfs_exec_spawn(const struct bfs_exec *execbuf) {
 		bfs_exec_debug(execbuf, "Executing '%s' ... [%zu arguments]\n", execbuf->argv[0], execbuf->argc - 1);
 	}
 
-	// Use a pipe to report errors from the child
-	int pipefd[2] = {-1, -1};
-	if (pipe_cloexec(pipefd) != 0) {
-		bfs_exec_debug(execbuf, "pipe() failed: %s\n", strerror(errno));
-	}
-
-	pid_t pid = fork();
+	pid_t pid = -1;
+	int error;
 
-	if (pid < 0) {
-		close(pipefd[1]);
-		close(pipefd[0]);
+	struct bfs_spawn ctx;
+	if (bfs_spawn_init(&ctx) != 0) {
 		return -1;
-	} else if (pid > 0) {
-		// Parent
-		close(pipefd[1]);
-
-		int ret, error;
-		ssize_t nbytes = read(pipefd[0], &error, sizeof(error));
-		close(pipefd[0]);
-		if (nbytes == sizeof(error)) {
-			ret = -1;
-		} else {
-			ret = 0;
-			error = 0;
-		}
+	}
 
-		int wstatus;
-		if (waitpid(pid, &wstatus, 0) < 0) {
-			return -1;
-		}
+	if (bfs_spawn_setflags(&ctx, BFS_SPAWN_USEPATH) != 0) {
+		goto fail;
+	}
 
-		if (WIFEXITED(wstatus)) {
-			int status = WEXITSTATUS(wstatus);
-			if (status != EXIT_SUCCESS) {
-				bfs_exec_debug(execbuf, "Command '%s' failed with status %d\n", execbuf->argv[0], status);
-				ret = -1;
-			}
-		} else if (WIFSIGNALED(wstatus)) {
-			int sig = WTERMSIG(wstatus);
-			bfs_exec_debug(execbuf, "Command '%s' terminated by signal %d\n", execbuf->argv[0], sig);
-			ret = -1;
-		} else {
-			bfs_exec_debug(execbuf, "Command '%s' terminated abnormally\n", execbuf->argv[0]);
-			ret = -1;
+	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, environ);
+fail:
+	error = errno;
+	bfs_spawn_destroy(&ctx);
+	if (pid < 0) {
 		errno = error;
-		return ret;
-	} else {
-		// Child
-		close(pipefd[0]);
+		return -1;
+	}
 
-		if (execbuf->wd_fd >= 0) {
-			if (fchdir(execbuf->wd_fd) != 0) {
-				goto child_err;
-			}
-		}
+	int wstatus;
+	if (waitpid(pid, &wstatus, 0) < 0) {
+		return -1;
+	}
 
-		execvp(execbuf->argv[0], execbuf->argv);
+	int ret = -1;
 
-		int error;
-	child_err:
-		error = errno;
-		if (write(pipefd[1], &error, sizeof(error)) != sizeof(error)) {
-			// Parent will still see that we exited unsuccessfully, but won't know why
+	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);
 		}
-		close(pipefd[1]);
-		_Exit(EXIT_FAILURE);
+	} else if (WIFSIGNALED(wstatus)) {
+		int sig = WTERMSIG(wstatus);
+		bfs_exec_debug(execbuf, "Command '%s' terminated by signal %d\n", execbuf->argv[0], sig);
+	} else {
+		bfs_exec_debug(execbuf, "Command '%s' terminated abnormally\n", execbuf->argv[0]);
 	}
+
+	errno = 0;
+	return ret;
 }
 
 /** exec() a command for a single file. */
diff --git a/spawn.c b/spawn.c
new file mode 100644
index 0000000..82bce11
--- /dev/null
+++ b/spawn.c
@@ -0,0 +1,158 @@
+/****************************************************************************
+ * bfs                                                                      *
+ * Copyright (C) 2018 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 "spawn.h"
+#include "util.h"
+#include <errno.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+/**
+ * Types of spawn actions.
+ */
+enum bfs_spawn_op {
+	BFS_SPAWN_FCHDIR,
+};
+
+/**
+ * A spawn action.
+ */
+struct bfs_spawn_action {
+	struct bfs_spawn_action *next;
+
+	enum bfs_spawn_op op;
+	int fd;
+};
+
+int bfs_spawn_init(struct bfs_spawn *ctx) {
+	ctx->flags = 0;
+	ctx->actions = NULL;
+	ctx->tail = &ctx->actions;
+	return 0;
+}
+
+int bfs_spawn_destroy(struct bfs_spawn *ctx) {
+	struct bfs_spawn_action *action = ctx->actions;
+	while (action) {
+		struct bfs_spawn_action *next = action->next;
+		free(action);
+		action = next;
+	}
+	return 0;
+}
+
+int bfs_spawn_setflags(struct bfs_spawn *ctx, enum bfs_spawn_flags flags) {
+	ctx->flags = flags;
+	return 0;
+}
+
+static struct bfs_spawn_action *bfs_spawn_add(struct bfs_spawn *ctx, enum bfs_spawn_op op) {
+	struct bfs_spawn_action *action = malloc(sizeof(*action));
+	if (action) {
+		action->next = NULL;
+		action->op = op;
+		action->fd = -1;
+
+		*ctx->tail = action;
+		ctx->tail = &action->next;
+	}
+	return action;
+}
+
+int bfs_spawn_addfchdir(struct bfs_spawn *ctx, int fd) {
+	if (fd < 0) {
+		errno = EBADF;
+		return -1;
+	}
+
+	struct bfs_spawn_action *action = bfs_spawn_add(ctx, BFS_SPAWN_FCHDIR);
+	if (action) {
+		action->fd = fd;
+		return 0;
+	} else {
+		return -1;
+	}
+}
+
+static void bfs_spawn_exec(const char *file, const struct bfs_spawn *ctx, char **argv, char **envp, int pipefd[2]) {
+	int error;
+	enum bfs_spawn_flags flags = ctx ? ctx->flags : 0;
+	const struct bfs_spawn_action *actions = ctx ? ctx->actions : NULL;
+
+	close(pipefd[0]);
+
+	for (const struct bfs_spawn_action *action = actions; action; action = action->next) {
+		switch (action->op) {
+		case BFS_SPAWN_FCHDIR:
+			if (fchdir(action->fd) != 0) {
+				goto fail;
+			}
+			break;
+		}
+	}
+
+	if (flags & BFS_SPAWN_USEPATH) {
+		execvpe(file, argv, envp);
+	} else {
+		execve(file, argv, envp);
+	}
+
+fail:
+	error = errno;
+	while (write(pipefd[1], &error, sizeof(error)) < sizeof(error));
+	close(pipefd[1]);
+	_Exit(127);
+}
+
+pid_t bfs_spawn(const char *file, const struct bfs_spawn *ctx, char **argv, char **envp) {
+	// Use a pipe to report errors from the child
+	int pipefd[2];
+	if (pipe_cloexec(pipefd) != 0) {
+		return -1;
+	}
+
+	int error;
+	pid_t pid = fork();
+
+	if (pid < 0) {
+		error = errno;
+		close(pipefd[1]);
+		close(pipefd[0]);
+		errno = error;
+		return -1;
+	} else if (pid == 0) {
+		// Child
+		bfs_spawn_exec(file, ctx, argv, envp, pipefd);
+	}
+
+	// Parent
+	close(pipefd[1]);
+
+	ssize_t nbytes = read(pipefd[0], &error, sizeof(error));
+	close(pipefd[0]);
+	if (nbytes == sizeof(error)) {
+		int wstatus;
+		waitpid(pid, &wstatus, 0);
+		errno = error;
+		return -1;
+	}
+
+	return pid;
+}
diff --git a/spawn.h b/spawn.h
new file mode 100644
index 0000000..6a8a15c
--- /dev/null
+++ b/spawn.h
@@ -0,0 +1,43 @@
+/****************************************************************************
+ * bfs                                                                      *
+ * Copyright (C) 2018 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.           *
+ ****************************************************************************/
+
+#ifndef BFS_SPAWN_H
+#define BFS_SPAWN_H
+
+#include <stdbool.h>
+#include <signal.h>
+#include <sys/types.h>
+
+enum bfs_spawn_flags {
+	BFS_SPAWN_USEPATH = 1 << 0,
+};
+
+struct bfs_spawn {
+	enum bfs_spawn_flags flags;
+	struct bfs_spawn_action *actions;
+	struct bfs_spawn_action **tail;
+};
+
+int bfs_spawn_init(struct bfs_spawn *ctx);
+int bfs_spawn_destroy(struct bfs_spawn *ctx);
+
+int bfs_spawn_setflags(struct bfs_spawn *ctx, enum bfs_spawn_flags flags);
+
+int bfs_spawn_addfchdir(struct bfs_spawn *ctx, int fd);
+
+pid_t bfs_spawn(const char *file, const struct bfs_spawn *ctx, char **argv, char **envp);
+
+#endif // BFS_SPAWN_H
diff --git a/tests.sh b/tests.sh
index 1ad1568..c732979 100755
--- a/tests.sh
+++ b/tests.sh
@@ -438,7 +438,6 @@ bfs_tests=(
     test_expr_path_flag
     test_colors
     test_deep_strict
-    test_deep_stricter
 )
 
 BSD=yes
@@ -1523,14 +1522,6 @@ function test_deep_strict() {
     bfs_diff deep -mindepth 18 -exec /bin/bash -c 'echo "${1:0:6}/.../${1##*/} (${#1})"' /bin/bash '{}' \;
 }
 
-function test_deep_stricter() {
-    closefrom 4
-
-    # So few fds that pipe() fails in the -exec implementation
-    ulimit -n 6
-    bfs_diff deep -mindepth 18 -exec /bin/bash -c 'echo "${1:0:6}/.../${1##*/} (${#1})"' /bin/bash '{}' \;
-}
-
 function test_exit() {
     invoke_bfs basic -name foo -exit 42
     if [ $? -ne 42 ]; then
diff --git a/tests/test_deep_stricter.out b/tests/test_deep_stricter.out
deleted file mode 100644
index c385fce..0000000
--- a/tests/test_deep_stricter.out
+++ /dev/null
@@ -1,16 +0,0 @@
-deep/0/.../0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDE (4358)
-deep/1/.../0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDE (4358)
-deep/2/.../0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDE (4358)
-deep/3/.../0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDE (4358)
-deep/4/.../0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDE (4358)
-deep/5/.../0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDE (4358)
-deep/6/.../0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDE (4358)
-deep/7/.../0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDE (4358)
-deep/8/.../0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDE (4358)
-deep/9/.../0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDE (4358)
-deep/A/.../0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDE (4358)
-deep/B/.../0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDE (4358)
-deep/C/.../0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDE (4358)
-deep/D/.../0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDE (4358)
-deep/E/.../0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDE (4358)
-deep/F/.../0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDE (4358)