cpio: optional support for writing cpio files in newc format.

by pascal.bellard AT ads-lu.com.

function                                             old     new   delta
cpio_main                                            247    1122    +875
cpio_pad4                                              -      58     +58
gnu_dev_major                                         66      99     +33
gnu_dev_minor                                         38      57     +19
packed_usage                                       23964   23978     +14
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 4/0 up/down: 999/0)             Total: 999 bytes

3 files changed, 225 insertions, 19 deletions

diff --git a/archival/Config.in b/archival/Config.in
index 60c3ed2d5..28450612e 100644
--- a/archival/Config.in
+++ b/archival/Config.in
@@ -78,6 +78,14 @@ config CPIO
 	  Unless you have a specific application which requires cpio, you should
 	  probably say N here.
 
+config FEATURE_CPIO_O
+	bool "Support for archive creation"
+	default n
+	depends on CPIO
+	help
+	  This implementation of cpio can create cpio archives in the "newc"
+	  format only.
+
 config DPKG
 	bool "dpkg"
 	default n
diff --git a/archival/cpio.c b/archival/cpio.c
index 59ae60c77..c17219832 100644
--- a/archival/cpio.c
+++ b/archival/cpio.c
@@ -7,35 +7,225 @@
  * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
  *
  * Limitations:
- *		Doesn't check CRC's
- *		Only supports new ASCII and CRC formats
+ * Doesn't check CRC's
+ * Only supports new ASCII and CRC formats
  *
  */
 #include "libbb.h"
 #include "unarchive.h"
 
-#define CPIO_OPT_EXTRACT                0x01
-#define CPIO_OPT_TEST                   0x02
-#define CPIO_OPT_UNCONDITIONAL          0x04
-#define CPIO_OPT_VERBOSE                0x08
-#define CPIO_OPT_FILE                   0x10
-#define CPIO_OPT_CREATE_LEADING_DIR     0x20
-#define CPIO_OPT_PRESERVE_MTIME         0x40
+enum {
+	CPIO_OPT_EXTRACT            = (1 << 0),
+	CPIO_OPT_TEST               = (1 << 1),
+	CPIO_OPT_UNCONDITIONAL      = (1 << 2),
+	CPIO_OPT_VERBOSE            = (1 << 3),
+	CPIO_OPT_FILE               = (1 << 4),
+	CPIO_OPT_CREATE_LEADING_DIR = (1 << 5),
+	CPIO_OPT_PRESERVE_MTIME     = (1 << 6),
+	CPIO_OPT_CREATE             = (1 << 7),
+	CPIO_OPT_FORMAT             = (1 << 8),
+};
+
+#if ENABLE_FEATURE_CPIO_O
+static off_t cpio_pad4(off_t size)
+{
+	int i;
+
+	i = (- size) & 3;
+	size += i;
+	while (--i >= 0)
+		bb_putchar('\0');
+	return size;
+}
+
+/* Return value will become exit code.
+ * It's ok to exit instead of return. */
+static int cpio_o(void)
+{
+	struct name_s {
+		struct name_s *next;
+		char name[1];
+	};
+	struct inodes_s {
+		struct inodes_s *next;
+		struct name_s *names;
+		struct stat st;
+	};
+
+	struct inodes_s *links = NULL;
+	off_t bytes = 0; /* output bytes count */
+
+	while (1) {
+		const char *name;
+		char *line;
+		struct stat st;
+
+		line = xmalloc_fgetline(stdin);
+
+		if (line) {
+			/* Strip leading "./[./]..." from the filename */
+			name = line;
+			while (name[0] == '.' && name[1] == '/') {
+				while (*++name == '/')
+					continue;
+			}
+			if (!*name) { /* line is empty */
+				free(line);
+				continue;
+			}
+			if (lstat(name, &st)) {
+ abort_cpio_o:
+				bb_simple_perror_msg_and_die(name);
+			}
+
+			if (!(S_ISLNK(st.st_mode) || S_ISREG(st.st_mode)))
+				st.st_size = 0; /* paranoia */
+
+			/* Store hardlinks for later processing, dont output them */
+			if (!S_ISDIR(st.st_mode) && st.st_nlink > 1) {
+				struct name_s *n;
+				struct inodes_s *l;
+
+				/* Do we have this hardlink remembered? */
+				l = links;
+				while (1) {
+					if (l == NULL) {
+						/* Not found: add new item to "links" list */
+						l = xzalloc(sizeof(*l));
+						l->st = st;
+						l->next = links;
+						links = l;
+						break;
+					}
+					if (l->st.st_ino == st.st_ino) {
+						/* found */
+						break;
+					}
+					l = l->next;
+				}
+				/* Add new name to "l->names" list */
+				n = xmalloc(sizeof(*n) + strlen(name));
+				strcpy(n->name, name);
+				n->next = l->names;
+				l->names = n;
+
+				free(line);
+				continue;
+			}
+
+		} else { /* line == NULL: EOF */
+ next_link:
+			if (links) {
+				/* Output hardlink's data */
+				st = links->st;
+				name = links->names->name;
+				links->names = links->names->next;
+				/* GNU cpio is reported to emit file data
+				 * only for the last instance. Mimic that. */
+				if (links->names == NULL)
+					links = links->next;
+				else
+					st.st_size = 0;
+				/* NB: we leak links->names and/or links,
+				 * this is intended (we exit soon anyway) */
+			} else {
+				/* If no (more) hardlinks to output,
+				 * output "trailer" entry */
+				name = "TRAILER!!!";
+				/* st.st_size == 0 is a must, but for uniformity
+				 * in the output, we zero out everything */
+				memset(&st, 0, sizeof(st));
+				/* st.st_nlink = 1; - GNU cpio does this */
+			}
+		}
+
+		bytes += printf("070701"
+		                "%08X%08X%08X%08X%08X%08X%08X"
+		                "%08X%08X%08X%08X" /* GNU cpio uses uppercase hex */
+				/* strlen+1: */ "%08X"
+				/* chksum: */   "00000000" /* (only for "070702" files) */
+				/* name,NUL: */ "%s%c",
+		                (unsigned)(uint32_t) st.st_ino,
+		                (unsigned)(uint32_t) st.st_mode,
+		                (unsigned)(uint32_t) st.st_uid,
+		                (unsigned)(uint32_t) st.st_gid,
+		                (unsigned)(uint32_t) st.st_nlink,
+		                (unsigned)(uint32_t) st.st_mtime,
+		                (unsigned)(uint32_t) st.st_size,
+		                (unsigned)(uint32_t) major(st.st_dev),
+		                (unsigned)(uint32_t) minor(st.st_dev),
+		                (unsigned)(uint32_t) major(st.st_rdev),
+		                (unsigned)(uint32_t) minor(st.st_rdev),
+		                (unsigned)(strlen(name) + 1),
+		                name, '\0');
+		bytes = cpio_pad4(bytes);
+
+		if (st.st_size) {
+			if (S_ISLNK(st.st_mode)) {
+				char *lpath = xmalloc_readlink_or_warn(name);
+				if (!lpath)
+					goto abort_cpio_o;
+				bytes += printf("%s", lpath);
+				free(lpath);
+			} else { /* S_ISREG */
+				int fd = xopen(name, O_RDONLY);
+				fflush(stdout);
+				/* We must abort if file got shorter too! */
+				if (bb_copyfd_size(fd, STDOUT_FILENO, st.st_size) != st.st_size) {
+					bb_error_msg_and_die("I/O error, of file '%s' was truncated", name);
+				}
+				bytes += st.st_size;
+				close(fd);
+			}
+			bytes = cpio_pad4(bytes);
+		}
+
+		if (!line) {
+			if (links)
+				goto next_link;
+			/* TODO: GNU cpio pads trailer to 512 bytes, do we want that? */
+			return EXIT_SUCCESS;
+		}
+
+		free(line);
+	} /* end of "while (1)" */
+}
+#endif
 
 int cpio_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
-int cpio_main(int argc, char **argv)
+int cpio_main(int argc ATTRIBUTE_UNUSED, char **argv)
 {
 	archive_handle_t *archive_handle;
-	char *cpio_filename = NULL;
+	char *cpio_filename;
+#if ENABLE_FEATURE_CPIO_O
+	const char *cpio_fmt = "";
+#endif
 	unsigned opt;
 
-	/* Initialise */
+	/* Initialize */
 	archive_handle = init_handle();
 	archive_handle->src_fd = STDIN_FILENO;
 	archive_handle->seek = seek_by_read;
 	archive_handle->flags = ARCHIVE_EXTRACT_NEWER | ARCHIVE_PRESERVE_DATE;
 
+#if ENABLE_FEATURE_CPIO_O
+	opt = getopt32(argv, "ituvF:dmoH:", &cpio_filename, &cpio_fmt);
+
+	if (opt & CPIO_OPT_CREATE) {
+		if (*cpio_fmt != 'n')
+			bb_show_usage();
+		if (opt & CPIO_OPT_FILE) {
+			fclose(stdout);
+			stdout = fopen(cpio_filename, "w");
+			/* Paranoia: I don't trust libc that much */
+			xdup2(fileno(stdout), STDOUT_FILENO);
+		}
+		return cpio_o();
+	}
+#else
 	opt = getopt32(argv, "ituvF:dm", &cpio_filename);
+#endif
+	argv += optind;
 
 	/* One of either extract or test options must be given */
 	if ((opt & (CPIO_OPT_TEST | CPIO_OPT_EXTRACT)) == 0) {
@@ -63,7 +253,7 @@ int cpio_main(int argc, char **argv)
 			archive_handle->action_header = header_list;
 		}
 	}
-	if (cpio_filename) { /* CPIO_OPT_FILE */
+	if (opt & CPIO_OPT_FILE) { /* -F */
 		archive_handle->src_fd = xopen(cpio_filename, O_RDONLY);
 		archive_handle->seek = seek_by_jump;
 	}
@@ -71,13 +261,14 @@ int cpio_main(int argc, char **argv)
 		archive_handle->flags |= ARCHIVE_CREATE_LEADING_DIRS;
 	}
 
-	while (optind < argc) {
+	while (*argv) {
 		archive_handle->filter = filter_accept_list;
-		llist_add_to(&(archive_handle->accept), argv[optind]);
-		optind++;
+		llist_add_to(&(archive_handle->accept), *argv);
+		argv++;
 	}
 
-	while (get_header_cpio(archive_handle) == EXIT_SUCCESS);
+	while (get_header_cpio(archive_handle) == EXIT_SUCCESS)
+		continue;
 
 	return EXIT_SUCCESS;
 }
diff --git a/include/usage.h b/include/usage.h
index 529a228ec..0849c6831 100644
--- a/include/usage.h
+++ b/include/usage.h
@@ -509,13 +509,20 @@
      "\n	-l,-s	Create (sym)links" \
 
 #define cpio_trivial_usage \
-       "-[dimtuv][F cpiofile]"
+       "-[dim" USE_FEATURE_CPIO_O("o") "tuv][F cpiofile]" \
+       USE_FEATURE_CPIO_O( "[H newc]" ) 
 #define cpio_full_usage \
-       "Extract or list files from a cpio archive\n" \
+       "Extract or list files from a cpio archive" \
+	USE_FEATURE_CPIO_O( ", or create a cpio archive" ) \
+     "\n" \
        "Main operation mode:" \
      "\n	d	Make leading directories" \
      "\n	i	Extract" \
      "\n	m	Preserve mtime" \
+	USE_FEATURE_CPIO_O( \
+     "\n	o	Create" \
+     "\n	H newc	Define format" \
+	) \
      "\n	t	List" \
      "\n	v	Verbose" \
      "\n	u	Unconditional overwrite" \