tar: move vfork into separate function (smaller code)

open_transformer: more informative error messages

function                                             old     new   delta
vfork_compressor                                       -     210    +210
writeTarFile                                         547     299    -248
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 0/1 up/down: 210/-248)          Total: -38 bytes

2 files changed, 103 insertions, 95 deletions

diff --git a/archival/libunarchive/open_transformer.c b/archival/libunarchive/open_transformer.c
index 3c551de..8fb8602 100644
--- a/archival/libunarchive/open_transformer.c
+++ b/archival/libunarchive/open_transformer.c
@@ -22,11 +22,13 @@ int open_transformer(int src_fd,
 
 #if BB_MMU
 	pid = fork();
+	if (pid == -1)
+		bb_perror_msg_and_die("can't fork");
 #else
 	pid = vfork();
-#endif
 	if (pid == -1)
-		bb_perror_msg_and_die("fork failed");
+		bb_perror_msg_and_die("can't vfork");
+#endif
 
 	if (pid == 0) {
 		/* child process */
@@ -49,7 +51,7 @@ int open_transformer(int src_fd,
 			argv[2] = (char*)"-";
 			argv[3] = NULL;
 			BB_EXECVP(transform_prog, argv);
-			bb_perror_msg_and_die("exec failed");
+			bb_perror_msg_and_die("can't exec %s", transform_prog);
 		}
 #endif
 		/* notreached */
diff --git a/archival/tar.c b/archival/tar.c
index 0c90ac0..0aa216c 100644
--- a/archival/tar.c
+++ b/archival/tar.c
@@ -84,26 +84,26 @@ struct TarHeader {		  /* byte offset */
 */
 typedef struct HardLinkInfo HardLinkInfo;
 struct HardLinkInfo {
-	HardLinkInfo *next;	/* Next entry in list */
-	dev_t dev;			/* Device number */
-	ino_t ino;			/* Inode number */
-	short linkCount;	/* (Hard) Link Count */
-	char name[1];		/* Start of filename (must be last) */
+	HardLinkInfo *next;     /* Next entry in list */
+	dev_t dev;              /* Device number */
+	ino_t ino;              /* Inode number */
+	short linkCount;        /* (Hard) Link Count */
+	char name[1];           /* Start of filename (must be last) */
 };
 
 /* Some info to be carried along when creating a new tarball */
 typedef struct TarBallInfo TarBallInfo;
 struct TarBallInfo {
-	int tarFd;				/* Open-for-write file descriptor
-							   for the tarball */
-	struct stat statBuf;	/* Stat info for the tarball, letting
-							   us know the inode and device that the
-							   tarball lives, so we can avoid trying
-							   to include the tarball into itself */
-	int verboseFlag;		/* Whether to print extra stuff or not */
-	const llist_t *excludeList;	/* List of files to not include */
-	HardLinkInfo *hlInfoHead;	/* Hard Link Tracking Information */
-	HardLinkInfo *hlInfo;	/* Hard Link Info for the current file */
+	int tarFd;                      /* Open-for-write file descriptor
+	                                 * for the tarball */
+	struct stat statBuf;            /* Stat info for the tarball, letting
+	                                 * us know the inode and device that the
+	                                 * tarball lives, so we can avoid trying
+	                                 * to include the tarball into itself */
+	int verboseFlag;                /* Whether to print extra stuff or not */
+	const llist_t *excludeList;     /* List of files to not include */
+	HardLinkInfo *hlInfoHead;       /* Hard Link Tracking Information */
+	HardLinkInfo *hlInfo;           /* Hard Link Info for the current file */
 };
 
 /* A nice enum with all the possible tar file content types */
@@ -503,100 +503,104 @@ static int writeFileToTarball(const char *fileName, struct stat *statbuf,
 	return TRUE;
 }
 
-static int writeTarFile(const int tar_fd, const int verboseFlag,
-	const unsigned long dereferenceFlag, const llist_t *include,
-	const llist_t *exclude, const int gzip)
-{
-	pid_t gzipPid = 0;
-	int errorFlag = FALSE;
-	struct TarBallInfo tbInfo;
-
-	tbInfo.hlInfoHead = NULL;
-
-	fchmod(tar_fd, 0644);
-	tbInfo.tarFd = tar_fd;
-	tbInfo.verboseFlag = verboseFlag;
-
-	/* Store the stat info for the tarball's file, so
-	 * can avoid including the tarball into itself....  */
-	if (fstat(tbInfo.tarFd, &tbInfo.statBuf) < 0)
-		bb_perror_msg_and_die("cannot stat tar file");
-
 #if ENABLE_FEATURE_TAR_GZIP || ENABLE_FEATURE_TAR_BZIP2
-	if (gzip) {
+/* Don't inline: vfork scares gcc and pessimizes code */
+static void NOINLINE vfork_compressor(int tar_fd, int gzip)
+{
+	pid_t gzipPid;
 #if ENABLE_FEATURE_TAR_GZIP && ENABLE_FEATURE_TAR_BZIP2
-		const char *zip_exec = (gzip == 1) ? "gzip" : "bzip2";
+	const char *zip_exec = (gzip == 1) ? "gzip" : "bzip2";
 #elif ENABLE_FEATURE_TAR_GZIP
-		const char *zip_exec = "gzip";
+	const char *zip_exec = "gzip";
 #else /* only ENABLE_FEATURE_TAR_BZIP2 */
-		const char *zip_exec = "bzip2";
+	const char *zip_exec = "bzip2";
 #endif
 	// On Linux, vfork never unpauses parent early, although standard
 	// allows for that. Do we want to waste bytes checking for it?
 #define WAIT_FOR_CHILD 0
-		volatile int vfork_exec_errno = 0;
-#if WAIT_FOR_CHILD
-		struct fd_pair gzipStatusPipe;
-#endif
-		struct fd_pair gzipDataPipe;
-		xpiped_pair(gzipDataPipe);
+	volatile int vfork_exec_errno = 0;
+	struct fd_pair gzipDataPipe;
 #if WAIT_FOR_CHILD
-		xpiped_pair(gzipStatusPipe);
+	struct fd_pair gzipStatusPipe;
+	xpiped_pair(gzipStatusPipe);
 #endif
+	xpiped_pair(gzipDataPipe);
 
-		signal(SIGPIPE, SIG_IGN); /* we only want EPIPE on errors */
+	signal(SIGPIPE, SIG_IGN); /* we only want EPIPE on errors */
 
 #if defined(__GNUC__) && __GNUC__
-		/* Avoid vfork clobbering */
-		(void) &include;
-		(void) &errorFlag;
-		(void) &zip_exec;
+	/* Avoid vfork clobbering */
+	(void) &zip_exec;
 #endif
 
-		gzipPid = vfork();
-		if (gzipPid < 0)
-			bb_perror_msg_and_die("vfork gzip");
+	gzipPid = vfork();
+	if (gzipPid < 0)
+		bb_perror_msg_and_die("can't vfork");
 
-		if (gzipPid == 0) {
-			/* child */
-			/* NB: close _first_, then move fds! */
-			close(gzipDataPipe.wr);
+	if (gzipPid == 0) {
+		/* child */
+		/* NB: close _first_, then move fds! */
+		close(gzipDataPipe.wr);
 #if WAIT_FOR_CHILD
-			close(gzipStatusPipe.rd);
-			/* gzipStatusPipe.wr will close only on exec -
-			 * parent waits for this close to happen */
-			fcntl(gzipStatusPipe.wr, F_SETFD, FD_CLOEXEC);
+		close(gzipStatusPipe.rd);
+		/* gzipStatusPipe.wr will close only on exec -
+		 * parent waits for this close to happen */
+		fcntl(gzipStatusPipe.wr, F_SETFD, FD_CLOEXEC);
 #endif
-			xmove_fd(gzipDataPipe.rd, 0);
-			xmove_fd(tbInfo.tarFd, 1);
-			/* exec gzip/bzip2 program/applet */
-			BB_EXECLP(zip_exec, zip_exec, "-f", NULL);
-			vfork_exec_errno = errno;
-			_exit(1);
-		}
+		xmove_fd(gzipDataPipe.rd, 0);
+		xmove_fd(tar_fd, 1);
+		/* exec gzip/bzip2 program/applet */
+		BB_EXECLP(zip_exec, zip_exec, "-f", NULL);
+		vfork_exec_errno = errno;
+		_exit(1);
+	}
 
-		/* parent */
-		xmove_fd(gzipDataPipe.wr, tbInfo.tarFd);
-		close(gzipDataPipe.rd);
+	/* parent */
+	xmove_fd(gzipDataPipe.wr, tar_fd);
+	close(gzipDataPipe.rd);
 #if WAIT_FOR_CHILD
-		close(gzipStatusPipe.wr);
-		while (1) {
-			char buf;
-			int n;
-
-			/* Wait until child execs (or fails to) */
-			n = full_read(gzipStatusPipe.rd, &buf, 1);
-			if (n < 0 /* && errno == EAGAIN */)
-				continue;	/* try it again */
-
-		}
-		close(gzipStatusPipe.rd);
+	close(gzipStatusPipe.wr);
+	while (1) {
+		char buf;
+		int n;
+
+		/* Wait until child execs (or fails to) */
+		n = full_read(gzipStatusPipe.rd, &buf, 1);
+		if (n < 0 /* && errno == EAGAIN */)
+			continue;	/* try it again */
+	}
+	close(gzipStatusPipe.rd);
 #endif
-		if (vfork_exec_errno) {
-			errno = vfork_exec_errno;
-			bb_perror_msg_and_die("cannot exec %s", zip_exec);
-		}
+	if (vfork_exec_errno) {
+		errno = vfork_exec_errno;
+		bb_perror_msg_and_die("cannot exec %s", zip_exec);
 	}
+}
+#endif /* ENABLE_FEATURE_TAR_GZIP || ENABLE_FEATURE_TAR_BZIP2 */
+
+
+/* gcc 4.2.1 inlines it, making code bigger */
+static NOINLINE int writeTarFile(int tar_fd, int verboseFlag,
+	int dereferenceFlag, const llist_t *include,
+	const llist_t *exclude, int gzip)
+{
+	int errorFlag = FALSE;
+	struct TarBallInfo tbInfo;
+
+	tbInfo.hlInfoHead = NULL;
+
+	fchmod(tar_fd, 0644);
+	tbInfo.tarFd = tar_fd;
+	tbInfo.verboseFlag = verboseFlag;
+
+	/* Store the stat info for the tarball's file, so
+	 * can avoid including the tarball into itself....  */
+	if (fstat(tbInfo.tarFd, &tbInfo.statBuf) < 0)
+		bb_perror_msg_and_die("cannot stat tar file");
+
+#if ENABLE_FEATURE_TAR_GZIP || ENABLE_FEATURE_TAR_BZIP2
+	if (gzip)
+		vfork_compressor(tbInfo.tarFd, gzip);
 #endif
 
 	tbInfo.excludeList = exclude;
@@ -630,20 +634,22 @@ static int writeTarFile(const int tar_fd, const int verboseFlag,
 	if (errorFlag)
 		bb_error_msg("error exit delayed from previous errors");
 
-	if (gzipPid) {
+#if ENABLE_FEATURE_TAR_GZIP || ENABLE_FEATURE_TAR_BZIP2
+	if (gzip) {
 		int status;
-		if (safe_waitpid(gzipPid, &status, 0) == -1)
+		if (safe_waitpid(-1, &status, 0) == -1)
 			bb_perror_msg("waitpid");
 		else if (!WIFEXITED(status) || WEXITSTATUS(status))
 			/* gzip was killed or has exited with nonzero! */
 			errorFlag = TRUE;
 	}
+#endif
 	return errorFlag;
 }
 #else
-int writeTarFile(const int tar_fd, const int verboseFlag,
-	const unsigned long dereferenceFlag, const llist_t *include,
-	const llist_t *exclude, const int gzip);
+int writeTarFile(int tar_fd, int verboseFlag,
+	int dereferenceFlag, const llist_t *include,
+	const llist_t *exclude, int gzip);
 #endif /* FEATURE_TAR_CREATE */
 
 #if ENABLE_FEATURE_TAR_FROM