util: New close() wrappers to check for EBADF and preserve errno

9 files changed, 66 insertions, 53 deletions

diff --git a/bar.c b/bar.c
index 31734ac..b0e595e 100644
--- a/bar.c
+++ b/bar.c
@@ -1,6 +1,6 @@
 /****************************************************************************
  * bfs                                                                      *
- * Copyright (C) 2020 Tavian Barnes <tavianator@tavianator.com>             *
+ * Copyright (C) 2020-2022 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.                           *
@@ -155,28 +155,24 @@ static int bfs_bar_printf(struct bfs_bar *bar, const char *format, ...) {
 }
 
 struct bfs_bar *bfs_bar_show(void) {
-	int error;
-
 	if (the_bar.fd >= 0) {
-		error = EBUSY;
+		errno = EBUSY;
 		goto fail;
 	}
 
 	char term[L_ctermid];
 	ctermid(term);
 	if (strlen(term) == 0) {
-		error = ENOTTY;
+		errno = ENOTTY;
 		goto fail;
 	}
 
 	the_bar.fd = open(term, O_RDWR | O_CLOEXEC);
 	if (the_bar.fd < 0) {
-		error = errno;
 		goto fail;
 	}
 
 	if (bfs_bar_getsize(&the_bar) != 0) {
-		error = errno;
 		goto fail_close;
 	}
 
@@ -207,10 +203,9 @@ struct bfs_bar *bfs_bar_show(void) {
 	return &the_bar;
 
 fail_close:
-	close(the_bar.fd);
+	close_quietly(the_bar.fd);
 	the_bar.fd = -1;
 fail:
-	errno = error;
 	return NULL;
 }
 
@@ -248,6 +243,6 @@ void bfs_bar_hide(struct bfs_bar *bar) {
 
 	bfs_bar_reset(bar);
 
-	close(bar->fd);
+	xclose(bar->fd);
 	bar->fd = -1;
 }
diff --git a/bftw.c b/bftw.c
index 64b1120..5f5afff 100644
--- a/bftw.c
+++ b/bftw.c
@@ -1,6 +1,6 @@
 /****************************************************************************
  * bfs                                                                      *
- * Copyright (C) 2015-2021 Tavian Barnes <tavianator@tavianator.com>        *
+ * Copyright (C) 2015-2022 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.                           *
@@ -244,7 +244,7 @@ static void bftw_file_close(struct bftw_cache *cache, struct bftw_file *file) {
 
 	bftw_cache_remove(cache, file);
 
-	close(file->fd);
+	xclose(file->fd);
 	file->fd = -1;
 }
 
diff --git a/dir.c b/dir.c
index 90c2e3e..024e767 100644
--- a/dir.c
+++ b/dir.c
@@ -138,12 +138,10 @@ struct bfs_dir *bfs_opendir(int at_fd, const char *at_path) {
 #else
 	dir->dir = fdopendir(fd);
 	if (!dir->dir) {
-		int error = errno;
 		if (at_path) {
-			close(fd);
+			close_quietly(fd);
 		}
 		free(dir);
-		errno = error;
 		return NULL;
 	}
 
@@ -280,7 +278,7 @@ int bfs_readdir(struct bfs_dir *dir, struct bfs_dirent *de) {
 
 int bfs_closedir(struct bfs_dir *dir) {
 #if __linux__
-	int ret = close(dir->fd);
+	int ret = xclose(dir->fd);
 #else
 	int ret = closedir(dir->dir);
 #endif
diff --git a/exec.c b/exec.c
index 45233e1..310756b 100644
--- a/exec.c
+++ b/exec.c
@@ -1,6 +1,6 @@
 /****************************************************************************
  * bfs                                                                      *
- * Copyright (C) 2017-2018 Tavian Barnes <tavianator@tavianator.com>        *
+ * 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.                           *
@@ -308,12 +308,10 @@ static int bfs_exec_openwd(struct bfs_exec *execbuf, const struct BFTW *ftwbuf)
 }
 
 /** Close the working directory. */
-static int bfs_exec_closewd(struct bfs_exec *execbuf, const struct BFTW *ftwbuf) {
-	int ret = 0;
-
+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) {
-			ret = close(execbuf->wd_fd);
+			xclose(execbuf->wd_fd);
 		}
 		execbuf->wd_fd = -1;
 	}
@@ -323,8 +321,6 @@ static int bfs_exec_closewd(struct bfs_exec *execbuf, const struct BFTW *ftwbuf)
 		execbuf->wd_path = NULL;
 		execbuf->wd_len = 0;
 	}
-
-	return ret;
 }
 
 /** Actually spawn the process. */
diff --git a/main.c b/main.c
index 7ceb0a2..ade5358 100644
--- a/main.c
+++ b/main.c
@@ -1,6 +1,6 @@
 /****************************************************************************
  * bfs                                                                      *
- * Copyright (C) 2015-2021 Tavian Barnes <tavianator@tavianator.com>        *
+ * Copyright (C) 2015-2022 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.                           *
@@ -54,6 +54,7 @@
 #include "ctx.h"
 #include "eval.h"
 #include "parse.h"
+#include "util.h"
 #include <errno.h>
 #include <fcntl.h>
 #include <locale.h>
@@ -79,9 +80,7 @@ static int redirect(int fd, const char *path, int flags) {
 	}
 
 	int ret = dup2(newfd, fd);
-	int err = errno;
-	close(newfd);
-	errno = err;
+	close_quietly(newfd);
 	return ret;
 }
 
diff --git a/parse.c b/parse.c
index aea7b4f..8ff47c2 100644
--- a/parse.c
+++ b/parse.c
@@ -1,6 +1,6 @@
 /****************************************************************************
  * bfs                                                                      *
- * Copyright (C) 2015-2021 Tavian Barnes <tavianator@tavianator.com>        *
+ * Copyright (C) 2015-2022 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.                           *
@@ -2743,7 +2743,7 @@ static CFILE *launch_pager(pid_t *pid, CFILE *cout) {
 		goto fail_ctx;
 	}
 
-	close(pipefd[0]);
+	xclose(pipefd[0]);
 	bfs_spawn_destroy(&ctx);
 	free(exe);
 	return ret;
@@ -2758,10 +2758,10 @@ fail_file:
 	}
 fail_pipe:
 	if (pipefd[1] >= 0) {
-		close(pipefd[1]);
+		xclose(pipefd[1]);
 	}
 	if (pipefd[0] >= 0) {
-		close(pipefd[0]);
+		xclose(pipefd[0]);
 	}
 fail_exe:
 	free(exe);
diff --git a/spawn.c b/spawn.c
index d4ff4fd..31f9897 100644
--- a/spawn.c
+++ b/spawn.c
@@ -1,6 +1,6 @@
 /****************************************************************************
  * bfs                                                                      *
- * Copyright (C) 2018-2019 Tavian Barnes <tavianator@tavianator.com>        *
+ * Copyright (C) 2018-2022 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.                           *
@@ -146,7 +146,7 @@ static void bfs_spawn_exec(const char *exe, const struct bfs_spawn *ctx, char **
 	int error;
 	const struct bfs_spawn_action *actions = ctx ? ctx->actions : NULL;
 
-	close(pipefd[0]);
+	xclose(pipefd[0]);
 
 	for (const struct bfs_spawn_action *action = actions; action; action = action->next) {
 		// Move the error-reporting pipe out of the way if necessary...
@@ -155,7 +155,7 @@ static void bfs_spawn_exec(const char *exe, const struct bfs_spawn *ctx, char **
 			if (fd < 0) {
 				goto fail;
 			}
-			close(pipefd[1]);
+			xclose(pipefd[1]);
 			pipefd[1] = fd;
 		}
 
@@ -198,7 +198,7 @@ fail:
 	// unsuccessfully, but won't know why
 	(void) xwrite(pipefd[1], &error, sizeof(error));
 
-	close(pipefd[1]);
+	xclose(pipefd[1]);
 	_Exit(127);
 }
 
@@ -224,15 +224,11 @@ pid_t bfs_spawn(const char *exe, const struct bfs_spawn *ctx, char **argv, char
 		return -1;
 	}
 
-	int error;
 	pid_t pid = fork();
-
 	if (pid < 0) {
-		error = errno;
-		close(pipefd[1]);
-		close(pipefd[0]);
+		close_quietly(pipefd[1]);
+		close_quietly(pipefd[0]);
 		free(resolved);
-		errno = error;
 		return -1;
 	} else if (pid == 0) {
 		// Child
@@ -240,11 +236,12 @@ pid_t bfs_spawn(const char *exe, const struct bfs_spawn *ctx, char **argv, char
 	}
 
 	// Parent
-	close(pipefd[1]);
+	xclose(pipefd[1]);
 	free(resolved);
 
+	int error;
 	ssize_t nbytes = xread(pipefd[0], &error, sizeof(error));
-	close(pipefd[0]);
+	xclose(pipefd[0]);
 	if (nbytes == sizeof(error)) {
 		int wstatus;
 		waitpid(pid, &wstatus, 0);
diff --git a/util.c b/util.c
index fa7a5b6..71b3c53 100644
--- a/util.c
+++ b/util.c
@@ -1,6 +1,6 @@
 /****************************************************************************
  * bfs                                                                      *
- * Copyright (C) 2016-2021 Tavian Barnes <tavianator@tavianator.com>        *
+ * Copyright (C) 2016-2022 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.                           *
@@ -89,7 +89,7 @@ int dup_cloexec(int fd) {
 	}
 
 	if (fcntl(ret, F_SETFD, FD_CLOEXEC) == -1) {
-		close(ret);
+		close_quietly(ret);
 		return -1;
 	}
 
@@ -106,10 +106,8 @@ int pipe_cloexec(int pipefd[2]) {
 	}
 
 	if (fcntl(pipefd[0], F_SETFD, FD_CLOEXEC) == -1 || fcntl(pipefd[1], F_SETFD, FD_CLOEXEC) == -1) {
-		int error = errno;
-		close(pipefd[1]);
-		close(pipefd[0]);
-		errno = error;
+		close_quietly(pipefd[1]);
+		close_quietly(pipefd[0]);
 		return -1;
 	}
 
@@ -464,11 +462,23 @@ FILE *xfopen(const char *path, int flags) {
 
 	FILE *ret = fdopen(fd, mode);
 	if (!ret) {
-		int error = errno;
-		close(fd);
-		errno = error;
+		close_quietly(fd);
 		return NULL;
 	}
 
 	return ret;
 }
+
+int xclose(int fd) {
+	int ret = close(fd);
+	if (ret != 0) {
+		assert(errno != EBADF);
+	}
+	return ret;
+}
+
+void close_quietly(int fd) {
+	int error = errno;
+	xclose(fd);
+	errno = error;
+}
diff --git a/util.h b/util.h
index ccac549..37c03fa 100644
--- a/util.h
+++ b/util.h
@@ -1,6 +1,6 @@
 /****************************************************************************
  * bfs                                                                      *
- * Copyright (C) 2016-2021 Tavian Barnes <tavianator@tavianator.com>        *
+ * Copyright (C) 2016-2022 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.                           *
@@ -298,4 +298,22 @@ char *xgetdelim(FILE *file, char delim);
  */
 FILE *xfopen(const char *path, int flags);
 
+/**
+ * close() wrapper that asserts the file descriptor is valid.
+ *
+ * @param fd
+ *         The file descriptor to close.
+ * @return
+ *         0 on success, or -1 on error.
+ */
+int xclose(int fd);
+
+/**
+ * close() variant that preserves errno.
+ *
+ * @param fd
+ *         The file descriptor to close.
+ */
+void close_quietly(int fd);
+
 #endif // BFS_UTIL_H