Replace direct file I/O with abstraction layer

This should make it easier to use libsquashfs with custom setups that
embedd a squashfs image inside something else. Also, it should make
it easier to port to non unix-like platforms.

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

7 files changed, 36 insertions, 33 deletions

diff --git a/lib/sqfs/comp/compressor.c b/lib/sqfs/comp/compressor.c
index 4d073f2..c938fe2 100644
--- a/lib/sqfs/comp/compressor.c
+++ b/lib/sqfs/comp/compressor.c
@@ -43,29 +43,31 @@ static const char *names[] = {
 	[SQFS_COMP_ZSTD] = "zstd",
 };
 
-int sqfs_generic_write_options(int fd, const void *data, size_t size)
+int sqfs_generic_write_options(sqfs_file_t *file, const void *data, size_t size)
 {
 	uint8_t buffer[size + 2];
+	int ret;
 
 	*((uint16_t *)buffer) = htole16(0x8000 | size);
 	memcpy(buffer + 2, data, size);
 
-	if (write_data("writing compressor options",
-		       fd, buffer, sizeof(buffer))) {
-		return SQFS_ERROR_IO;
-	}
+	ret = file->write_at(file, sizeof(sqfs_super_t),
+			     buffer, sizeof(buffer));
+	if (ret)
+		return ret;
 
 	return sizeof(buffer);
 }
 
-int sqfs_generic_read_options(int fd, void *data, size_t size)
+int sqfs_generic_read_options(sqfs_file_t *file, void *data, size_t size)
 {
 	uint8_t buffer[size + 2];
+	int ret;
 
-	if (read_data_at("reading compressor options", sizeof(sqfs_super_t),
-			 fd, buffer, sizeof(buffer))) {
-		return SQFS_ERROR_IO;
-	}
+	ret = file->read_at(file, sizeof(sqfs_super_t),
+			    buffer, sizeof(buffer));
+	if (ret)
+		return ret;
 
 	if (le16toh(*((uint16_t *)buffer)) != (0x8000 | size))
 		return SQFS_ERROR_CORRUPTED;
diff --git a/lib/sqfs/comp/gzip.c b/lib/sqfs/comp/gzip.c
index 484901a..bec217a 100644
--- a/lib/sqfs/comp/gzip.c
+++ b/lib/sqfs/comp/gzip.c
@@ -44,7 +44,7 @@ static void gzip_destroy(sqfs_compressor_t *base)
 	free(gzip);
 }
 
-static int gzip_write_options(sqfs_compressor_t *base, int fd)
+static int gzip_write_options(sqfs_compressor_t *base, sqfs_file_t *file)
 {
 	gzip_compressor_t *gzip = (gzip_compressor_t *)base;
 	gzip_options_t opt;
@@ -59,16 +59,16 @@ static int gzip_write_options(sqfs_compressor_t *base, int fd)
 	opt.window = htole16(gzip->opt.window);
 	opt.strategies = htole16(gzip->opt.strategies);
 
-	return sqfs_generic_write_options(fd, &opt, sizeof(opt));
+	return sqfs_generic_write_options(file, &opt, sizeof(opt));
 }
 
-static int gzip_read_options(sqfs_compressor_t *base, int fd)
+static int gzip_read_options(sqfs_compressor_t *base, sqfs_file_t *file)
 {
 	gzip_compressor_t *gzip = (gzip_compressor_t *)base;
 	gzip_options_t opt;
 	int ret;
 
-	ret = sqfs_generic_read_options(fd, &opt, sizeof(opt));
+	ret = sqfs_generic_read_options(file, &opt, sizeof(opt));
 	if (ret)
 		return ret;
 
diff --git a/lib/sqfs/comp/internal.h b/lib/sqfs/comp/internal.h
index d2410fc..29b875f 100644
--- a/lib/sqfs/comp/internal.h
+++ b/lib/sqfs/comp/internal.h
@@ -12,13 +12,15 @@
 #include "sqfs/predef.h"
 #include "sqfs/compress.h"
 #include "sqfs/error.h"
+#include "sqfs/io.h"
 #include "util.h"
 
 SQFS_INTERNAL
-int sqfs_generic_write_options(int fd, const void *data, size_t size);
+int sqfs_generic_write_options(sqfs_file_t *file, const void *data,
+			       size_t size);
 
 SQFS_INTERNAL
-int sqfs_generic_read_options(int fd, void *data, size_t size);
+int sqfs_generic_read_options(sqfs_file_t *file, void *data, size_t size);
 
 SQFS_INTERNAL
 sqfs_compressor_t *xz_compressor_create(const sqfs_compressor_config_t *cfg);
diff --git a/lib/sqfs/comp/lz4.c b/lib/sqfs/comp/lz4.c
index 446b83e..e96ab45 100644
--- a/lib/sqfs/comp/lz4.c
+++ b/lib/sqfs/comp/lz4.c
@@ -28,7 +28,7 @@ typedef struct {
 
 #define LZ4LEGACY 1
 
-static int lz4_write_options(sqfs_compressor_t *base, int fd)
+static int lz4_write_options(sqfs_compressor_t *base, sqfs_file_t *file)
 {
 	lz4_compressor_t *lz4 = (lz4_compressor_t *)base;
 	lz4_options opt = {
@@ -37,16 +37,16 @@ static int lz4_write_options(sqfs_compressor_t *base, int fd)
 				 SQFS_COMP_FLAG_LZ4_HC : 0),
 	};
 
-	return sqfs_generic_write_options(fd, &opt, sizeof(opt));
+	return sqfs_generic_write_options(file, &opt, sizeof(opt));
 }
 
-static int lz4_read_options(sqfs_compressor_t *base, int fd)
+static int lz4_read_options(sqfs_compressor_t *base, sqfs_file_t *file)
 {
 	lz4_options opt;
 	int ret;
 	(void)base;
 
-	ret = sqfs_generic_read_options(fd, &opt, sizeof(opt));
+	ret = sqfs_generic_read_options(file, &opt, sizeof(opt));
 	if (ret)
 		return ret;
 
diff --git a/lib/sqfs/comp/lzo.c b/lib/sqfs/comp/lzo.c
index b4cfebf..e4a7ca6 100644
--- a/lib/sqfs/comp/lzo.c
+++ b/lib/sqfs/comp/lzo.c
@@ -59,7 +59,7 @@ typedef struct {
 	uint32_t level;
 } lzo_options_t;
 
-static int lzo_write_options(sqfs_compressor_t *base, int fd)
+static int lzo_write_options(sqfs_compressor_t *base, sqfs_file_t *file)
 {
 	lzo_compressor_t *lzo = (lzo_compressor_t *)base;
 	lzo_options_t opt;
@@ -77,16 +77,16 @@ static int lzo_write_options(sqfs_compressor_t *base, int fd)
 		opt.level = 0;
 	}
 
-	return sqfs_generic_write_options(fd, &opt, sizeof(opt));
+	return sqfs_generic_write_options(file, &opt, sizeof(opt));
 }
 
-static int lzo_read_options(sqfs_compressor_t *base, int fd)
+static int lzo_read_options(sqfs_compressor_t *base, sqfs_file_t *file)
 {
 	lzo_compressor_t *lzo = (lzo_compressor_t *)base;
 	lzo_options_t opt;
 	int ret;
 
-	ret = sqfs_generic_read_options(fd, &opt, sizeof(opt));
+	ret = sqfs_generic_read_options(file, &opt, sizeof(opt));
 	if (ret)
 		return ret;
 
diff --git a/lib/sqfs/comp/xz.c b/lib/sqfs/comp/xz.c
index c626f92..24602ec 100644
--- a/lib/sqfs/comp/xz.c
+++ b/lib/sqfs/comp/xz.c
@@ -36,7 +36,7 @@ static bool is_dict_size_valid(size_t size)
 	return size == (x | (x >> 1));
 }
 
-static int xz_write_options(sqfs_compressor_t *base, int fd)
+static int xz_write_options(sqfs_compressor_t *base, sqfs_file_t *file)
 {
 	xz_compressor_t *xz = (xz_compressor_t *)base;
 	xz_options_t opt;
@@ -47,16 +47,16 @@ static int xz_write_options(sqfs_compressor_t *base, int fd)
 	opt.dict_size = htole32(xz->dict_size);
 	opt.flags = htole32(xz->flags);
 
-	return sqfs_generic_write_options(fd, &opt, sizeof(opt));
+	return sqfs_generic_write_options(file, &opt, sizeof(opt));
 }
 
-static int xz_read_options(sqfs_compressor_t *base, int fd)
+static int xz_read_options(sqfs_compressor_t *base, sqfs_file_t *file)
 {
 	xz_compressor_t *xz = (xz_compressor_t *)base;
 	xz_options_t opt;
 	int ret;
 
-	ret = sqfs_generic_read_options(fd, &opt, sizeof(opt));
+	ret = sqfs_generic_read_options(file, &opt, sizeof(opt));
 	if (ret)
 		return ret;
 
diff --git a/lib/sqfs/comp/zstd.c b/lib/sqfs/comp/zstd.c
index dc2387d..5434e1f 100644
--- a/lib/sqfs/comp/zstd.c
+++ b/lib/sqfs/comp/zstd.c
@@ -25,26 +25,25 @@ typedef struct {
 	uint32_t level;
 } zstd_options_t;
 
-static int zstd_write_options(sqfs_compressor_t *base, int fd)
+static int zstd_write_options(sqfs_compressor_t *base, sqfs_file_t *file)
 {
 	zstd_compressor_t *zstd = (zstd_compressor_t *)base;
 	zstd_options_t opt;
-	(void)fd;
 
 	if (zstd->level == SQFS_ZSTD_DEFAULT_LEVEL)
 		return 0;
 
 	opt.level = htole32(zstd->level);
-	return sqfs_generic_write_options(fd, &opt, sizeof(opt));
+	return sqfs_generic_write_options(file, &opt, sizeof(opt));
 }
 
-static int zstd_read_options(sqfs_compressor_t *base, int fd)
+static int zstd_read_options(sqfs_compressor_t *base, sqfs_file_t *file)
 {
 	zstd_options_t opt;
 	int ret;
 	(void)base;
 
-	ret = sqfs_generic_read_options(fd, &opt, sizeof(opt));
+	ret = sqfs_generic_read_options(file, &opt, sizeof(opt));
 	if (ret)
 		return ret;