cleanup: move error handling into write_retry

If write_retry fails to write everything, it is *always* an error.

This commit renames write_retry to write_data and moves error handling
into the function, making a lot of error handling code redundant.

Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>

13 files changed, 48 insertions, 152 deletions

diff --git a/include/util.h b/include/util.h
index 997cbf5..aff313f 100644
--- a/include/util.h
+++ b/include/util.h
@@ -23,9 +23,11 @@ int canonicalize_name(char *filename);
 
 /*
   A wrapper around the write() system call. It retries the write if it is
-  interrupted by a signal or only part of the data was written.
+  interrupted by a signal or only part of the data was written. Returns 0
+  on success. Writes to stderr on failure using 'errstr' as a perror style
+  error prefix.
 */
-ssize_t write_retry(int fd, const void *data, size_t size);
+int write_data(const char *errstr, int fd, const void *data, size_t size);
 
 /*
   A wrapper around the read() system call. It retries the read if it is
diff --git a/lib/Makemodule.am b/lib/Makemodule.am
index 865d99a..710db78 100644
--- a/lib/Makemodule.am
+++ b/lib/Makemodule.am
@@ -36,7 +36,7 @@ libsquashfs_a_SOURCES += lib/sqfs/data_writer.c lib/sqfs/write_xattr.c
 libsquashfs_a_SOURCES += include/data_writer.h include/frag_reader.h
 libsquashfs_a_SOURCES += include/data_reader.h lib/sqfs/data_reader.c
 
-libutil_a_SOURCES = lib/util/canonicalize_name.c lib/util/write_retry.c
+libutil_a_SOURCES = lib/util/canonicalize_name.c lib/util/write_data.c
 libutil_a_SOURCES += lib/util/read_retry.c include/util.h
 libutil_a_SOURCES += lib/util/print_version.c lib/util/mkdir_p.c
 libutil_a_SOURCES += lib/util/str_table.c include/str_table.h
diff --git a/lib/comp/compressor.c b/lib/comp/compressor.c
index cc04aa6..96bc3b1 100644
--- a/lib/comp/compressor.c
+++ b/lib/comp/compressor.c
@@ -59,24 +59,16 @@ static const char *names[] = {
 int generic_write_options(int fd, const void *data, size_t size)
 {
 	uint8_t buffer[size + 2];
-	ssize_t ret;
 
 	*((uint16_t *)buffer) = htole16(0x8000 | size);
 	memcpy(buffer + 2, data, size);
 
-	ret = write_retry(fd, buffer, sizeof(buffer));
-
-	if (ret < 0) {
-		perror("writing compressor options");
-		return -1;
-	}
-
-	if ((size_t)ret < sizeof(buffer)) {
-		fputs("writing compressor options: truncated write\n", stderr);
+	if (write_data("writing compressor options",
+		       fd, buffer, sizeof(buffer))) {
 		return -1;
 	}
 
-	return ret;
+	return sizeof(buffer);
 }
 
 int generic_read_options(int fd, void *data, size_t size)
diff --git a/lib/sqfs/data_reader.c b/lib/sqfs/data_reader.c
index ec85412..7f857b2 100644
--- a/lib/sqfs/data_reader.c
+++ b/lib/sqfs/data_reader.c
@@ -133,12 +133,10 @@ int data_reader_dump_file(data_reader_t *data, file_info_t *fi, int outfd,
 				ptr = data->buffer;
 			}
 
-			ret = write_retry(outfd, ptr, unpackedsz);
-			if (ret < 0)
-				goto fail_wr;
-
-			if ((size_t)ret < bs)
-				goto fail_wr_trunc;
+			if (write_data("writing uncompressed block",
+					outfd, ptr, unpackedsz)) {
+				return -1;
+			}
 		}
 	}
 
@@ -152,12 +150,10 @@ int data_reader_dump_file(data_reader_t *data, file_info_t *fi, int outfd,
 			return -1;
 		}
 
-		ret = write_retry(outfd, data->buffer, fragsz);
-		if (ret < 0)
-			goto fail_wr;
-
-		if ((size_t)ret < fragsz)
-			goto fail_wr_trunc;
+		if (write_data("writing uncompressed fragment",
+			       outfd, data->buffer, fragsz)) {
+			return -1;
+		}
 	}
 
 	return 0;
@@ -167,12 +163,6 @@ fail_sparse:
 fail_seek:
 	perror("seek on squashfs");
 	return -1;
-fail_wr:
-	perror("writing uncompressed block");
-	return -1;
-fail_wr_trunc:
-	fputs("writing uncompressed block: truncated write\n", stderr);
-	return -1;
 fail_rd:
 	perror("reading from squashfs");
 	return -1;
diff --git a/lib/sqfs/data_writer.c b/lib/sqfs/data_writer.c
index cbe2351..eebd2a4 100644
--- a/lib/sqfs/data_writer.c
+++ b/lib/sqfs/data_writer.c
@@ -41,24 +41,16 @@ static int write_compressed(data_writer_t *data, const void *in, size_t size,
 
 	if (ret > 0 && (size_t)ret < size) {
 		size = ret;
-		ret = write_retry(data->outfd, data->scratch, size);
+		in = data->scratch;
 		*outsize = size;
 	} else {
-		ret = write_retry(data->outfd, in, size);
 		*outsize = size | (1 << 24);
 	}
 
-	if (ret < 0) {
-		perror("writing to output file");
+	if (write_data("writing data block", data->outfd, in, size))
 		return -1;
-	}
-
-	if ((size_t)ret < size) {
-		fputs("write to output file truncated\n", stderr);
-		return -1;
-	}
 
-	data->super->bytes_used += ret;
+	data->super->bytes_used += size;
 	return 0;
 }
 
diff --git a/lib/sqfs/meta_writer.c b/lib/sqfs/meta_writer.c
index ef869e7..d55af3d 100644
--- a/lib/sqfs/meta_writer.c
+++ b/lib/sqfs/meta_writer.c
@@ -38,24 +38,10 @@ struct meta_writer_t {
 
 static int write_block(int fd, meta_block_t *outblk)
 {
-	size_t count;
-	ssize_t ret;
-
-	count = le16toh(((uint16_t *)outblk->data)[0]) & 0x7FFF;
-
-	ret = write_retry(fd, outblk->data, count + 2);
-
-	if (ret < 0) {
-		perror("writing meta data block");
-		return -1;
-	}
-
-	if ((size_t)ret < count) {
-		fputs("meta data written to file was truncated\n", stderr);
-		return -1;
-	}
+	size_t count = le16toh(((uint16_t *)outblk->data)[0]) & 0x7FFF;
 
-	return 0;
+	return write_data("writing meta data block", fd,
+			  outblk->data, count + 2);
 }
 
 meta_writer_t *meta_writer_create(int fd, compressor_t *cmp, bool keep_in_mem)
diff --git a/lib/sqfs/super.c b/lib/sqfs/super.c
index d3b79c6..59eb366 100644
--- a/lib/sqfs/super.c
+++ b/lib/sqfs/super.c
@@ -47,7 +47,6 @@ int sqfs_super_init(sqfs_super_t *super, size_t block_size, uint32_t mtime,
 int sqfs_super_write(sqfs_super_t *super, int fd)
 {
 	sqfs_super_t copy;
-	ssize_t ret;
 
 	copy.magic = htole32(super->magic);
 	copy.inode_count = htole32(super->inode_count);
@@ -72,18 +71,8 @@ int sqfs_super_write(sqfs_super_t *super, int fd)
 	if (lseek(fd, 0, SEEK_SET) == (off_t)-1)
 		goto fail_seek;
 
-	ret = write_retry(fd, &copy, sizeof(copy));
-
-	if (ret < 0) {
-		perror("squashfs writing super block");
+	if (write_data("writing super block", fd, &copy, sizeof(copy)))
 		return -1;
-	}
-
-	if ((size_t)ret < sizeof(copy)) {
-		fputs("squashfs writing super block: truncated write\n",
-		      stderr);
-		return -1;
-	}
 
 	if (lseek(fd, 0, SEEK_END) == (off_t)-1)
 		goto fail_seek;
diff --git a/lib/sqfs/table.c b/lib/sqfs/table.c
index fb6bddc..81e7691 100644
--- a/lib/sqfs/table.c
+++ b/lib/sqfs/table.c
@@ -15,7 +15,6 @@ int sqfs_write_table(int outfd, sqfs_super_t *super, const void *data,
 	size_t i, blkidx = 0, tblsize;
 	meta_writer_t *m;
 	uint32_t offset;
-	ssize_t ret;
 
 	/* Write actual data. Whenever we cross a block boundary, remember
 	   the block start offset */
@@ -49,16 +48,8 @@ int sqfs_write_table(int outfd, sqfs_super_t *super, const void *data,
 	*startblock = super->bytes_used;
 	tblsize = sizeof(blocks[0]) * blkidx;
 
-	ret = write_retry(outfd, blocks, tblsize);
-	if (ret < 0) {
-		perror("writing index table");
+	if (write_data("writing table index", outfd, blocks, tblsize))
 		return -1;
-	}
-
-	if ((size_t)ret < tblsize) {
-		fputs("index table truncated\n", stderr);
-		return -1;
-	}
 
 	super->bytes_used += tblsize;
 	return 0;
diff --git a/lib/sqfs/write_xattr.c b/lib/sqfs/write_xattr.c
index 0e11757..31fdf50 100644
--- a/lib/sqfs/write_xattr.c
+++ b/lib/sqfs/write_xattr.c
@@ -105,7 +105,6 @@ int write_xattr(int outfd, fstree_t *fs, sqfs_super_t *super,
 	meta_writer_t *mw;
 	tree_xattr_t *it;
 	uint32_t offset;
-	ssize_t ret;
 
 	if (fs->xattr == NULL)
 		return 0;
@@ -179,17 +178,13 @@ int write_xattr(int outfd, fstree_t *fs, sqfs_super_t *super,
 	idtbl.xattr_ids = htole32(count);
 	idtbl.unused = 0;
 
-	ret = write_retry(outfd, &idtbl, sizeof(idtbl));
-	if (ret < 0)
-		goto fail_wr;
-	if ((size_t)ret < sizeof(idtbl))
-		goto fail_trunc;
+	if (write_data("writing xattr ID table", outfd, &idtbl, sizeof(idtbl)))
+		goto fail_tbl;
 
-	ret = write_retry(outfd, tbl, sizeof(tbl[0]) * blocks);
-	if (ret < 0)
-		goto fail_wr;
-	if ((size_t)ret < sizeof(tbl[0]) * blocks)
-		goto fail_trunc;
+	if (write_data("writing xattr ID table",
+		       outfd, tbl, sizeof(tbl[0]) * blocks)) {
+		goto fail_tbl;
+	}
 
 	super->xattr_id_table_start = super->bytes_used;
 	super->bytes_used += sizeof(idtbl) + sizeof(tbl[0]) * blocks;
@@ -197,12 +192,6 @@ int write_xattr(int outfd, fstree_t *fs, sqfs_super_t *super,
 	free(tbl);
 	meta_writer_destroy(mw);
 	return 0;
-fail_wr:
-	perror("writing xattr ID table");
-	goto fail_tbl;
-fail_trunc:
-	fputs("writing xattr ID table: truncated write\n", stderr);
-	goto fail_tbl;
 fail_tbl:
 	free(tbl);
 fail_mw:
diff --git a/lib/tar/write_header.c b/lib/tar/write_header.c
index 70acb1a..caddc97 100644
--- a/lib/tar/write_header.c
+++ b/lib/tar/write_header.c
@@ -52,7 +52,6 @@ static int write_header(int fd, const struct stat *sb, const char *name,
 	int maj = 0, min = 0;
 	uint64_t size = 0;
 	tar_header_t hdr;
-	ssize_t ret;
 
 	if (S_ISCHR(sb->st_mode) || S_ISBLK(sb->st_mode)) {
 		maj = major(sb->st_rdev);
@@ -82,18 +81,7 @@ static int write_header(int fd, const struct stat *sb, const char *name,
 
 	update_checksum(&hdr);
 
-	ret = write_retry(fd, &hdr, sizeof(hdr));
-	if (ret < 0) {
-		perror("writing header record");
-		return -1;
-	}
-
-	if ((size_t)ret < sizeof(hdr)) {
-		fputs("writing header record: truncated write\n", stderr);
-		return -1;
-	}
-
-	return 0;
+	return write_data("writing tar header record", fd, &hdr, sizeof(hdr));
 }
 
 static int write_gnu_header(int fd, const struct stat *orig,
@@ -101,7 +89,6 @@ static int write_gnu_header(int fd, const struct stat *orig,
 			    int type, const char *name)
 {
 	struct stat sb;
-	ssize_t ret;
 
 	sb = *orig;
 	sb.st_mode = S_IFREG | 0644;
@@ -110,14 +97,8 @@ static int write_gnu_header(int fd, const struct stat *orig,
 	if (write_header(fd, &sb, name, NULL, type))
 		return -1;
 
-	ret = write_retry(fd, payload, payload_len);
-	if (ret < 0) {
-		perror("writing GNU extension header");
-		return -1;
-	}
-
-	if ((size_t)ret < payload_len) {
-		fputs("writing GNU extension header: truncated write\n", stderr);
+	if (write_data("writing GNU extension header",
+		       fd, payload, payload_len)) {
 		return -1;
 	}
 
diff --git a/lib/util/padd_file.c b/lib/util/padd_file.c
index 8598b8b..2f1ea9a 100644
--- a/lib/util/padd_file.c
+++ b/lib/util/padd_file.c
@@ -9,7 +9,6 @@ int padd_file(int outfd, uint64_t size, size_t blocksize)
 	size_t padd_sz = size % blocksize;
 	int status = -1;
 	uint8_t *buffer;
-	ssize_t ret;
 
 	if (padd_sz == 0)
 		return 0;
@@ -20,21 +19,15 @@ int padd_file(int outfd, uint64_t size, size_t blocksize)
 	if (buffer == NULL)
 		goto fail_errno;
 
-	ret = write_retry(outfd, buffer, padd_sz);
-
-	if (ret < 0)
-		goto fail_errno;
-
-	if ((size_t)ret < padd_sz)
-		goto fail_trunc;
+	if (write_data("padding output file to block size",
+		       outfd, buffer, padd_sz)) {
+		goto out;
+	}
 
 	status = 0;
 out:
 	free(buffer);
 	return status;
-fail_trunc:
-	fputs("padding output to block size: truncated write\n", stderr);
-	goto out;
 fail_errno:
 	perror("padding output file to block size");
 	goto out;
diff --git a/lib/util/write_retry.c b/lib/util/write_data.c
index 0ef856c..82f3aca 100644
--- a/lib/util/write_retry.c
+++ b/lib/util/write_data.c
@@ -1,27 +1,30 @@
 /* SPDX-License-Identifier: GPL-3.0-or-later */
 #include <unistd.h>
 #include <errno.h>
+#include <stdio.h>
 
 #include "util.h"
 
-ssize_t write_retry(int fd, const void *data, size_t size)
+int write_data(const char *errstr, int fd, const void *data, size_t size)
 {
-	ssize_t ret, total = 0;
+	ssize_t ret;
 
 	while (size > 0) {
 		ret = write(fd, data, size);
-		if (ret == 0)
-			break;
+		if (ret == 0) {
+			fprintf(stderr, "%s: write truncated\n", errstr);
+			return -1;
+		}
 		if (ret < 0) {
 			if (errno == EINTR)
 				continue;
+			perror(errstr);
 			return -1;
 		}
 
 		data = (const char *)data + ret;
 		size -= ret;
-		total += ret;
 	}
 
-	return total;
+	return 0;
 }
diff --git a/tar/sqfs2tar.c b/tar/sqfs2tar.c
index 110c8c4..15c0363 100644
--- a/tar/sqfs2tar.c
+++ b/tar/sqfs2tar.c
@@ -161,23 +161,11 @@ out_exit:
 static int terminate_archive(void)
 {
 	char buffer[1024];
-	ssize_t ret;
 
 	memset(buffer, '\0', sizeof(buffer));
 
-	ret = write_retry(STDOUT_FILENO, buffer, sizeof(buffer));
-
-	if (ret < 0) {
-		perror("adding archive terminator");
-		return -1;
-	}
-
-	if ((size_t)ret < sizeof(buffer)) {
-		fputs("adding archive terminator: truncated write\n", stderr);
-		return -1;
-	}
-
-	return 0;
+	return write_data("adding archive terminator", STDOUT_FILENO,
+			  buffer, sizeof(buffer));
 }
 
 static int write_tree_dfs(fstree_t *fs, tree_node_t *n, data_reader_t *data)