Overhaul sqfs_istream_t/sqfs_ostream_t error handling

Report an error number from the implementations, change the users to
forward that error number (which also means libtar write header/link
now returns an error code) and all subsequent binaries to use
sqfs_perror() instead of relying on the function to print an error
internally.

Also, make sure to preserve errno/GetLastError() in the implementations
and print out a stringified error in sqfs_perror() if the error code
indicates an I/O error.

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

2 files changed, 41 insertions, 6 deletions

diff --git a/lib/common/src/data_reader_dump.c b/lib/common/src/data_reader_dump.c
index e3cbb87..920b2bd 100644
--- a/lib/common/src/data_reader_dump.c
+++ b/lib/common/src/data_reader_dump.c
@@ -26,8 +26,7 @@ int sqfs_data_reader_dump(const char *name, sqfs_data_reader_t *data,
 		diff = (filesz < block_size) ? filesz : block_size;
 
 		if (SQFS_IS_SPARSE_BLOCK(inode->extra[i])) {
-			if (fp->append(fp, NULL, diff))
-				return -1;
+			err = fp->append(fp, NULL, diff);
 		} else {
 			err = sqfs_data_reader_get_block(data, inode, i,
 							 &chunk_size, &chunk);
@@ -38,11 +37,11 @@ int sqfs_data_reader_dump(const char *name, sqfs_data_reader_t *data,
 
 			err = fp->append(fp, chunk, chunk_size);
 			free(chunk);
-
-			if (err)
-				return -1;
 		}
 
+		if (err)
+			goto fail_io;
+
 		filesz -= diff;
 	}
 
@@ -58,8 +57,11 @@ int sqfs_data_reader_dump(const char *name, sqfs_data_reader_t *data,
 		free(chunk);
 
 		if (err)
-			return -1;
+			goto fail_io;
 	}
 
 	return 0;
+fail_io:
+	sqfs_perror(fp->get_filename(fp), "writing data block", err);
+	return -1;
 }
diff --git a/lib/common/src/perror.c b/lib/common/src/perror.c
index 53a8c16..5f62748 100644
--- a/lib/common/src/perror.c
+++ b/lib/common/src/perror.c
@@ -8,9 +8,22 @@
 
 #include <stdio.h>
 
+#if defined(_WIN32) || defined(__WINDOWS__)
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
+#else
+#include <errno.h>
+#include <string.h>
+#endif
+
 void sqfs_perror(const char *file, const char *action, int error_code)
 {
 	const char *errstr;
+#if defined(_WIN32) || defined(__WINDOWS__)
+	DWORD syserror = GetLastError();
+#else
+	int syserror = errno;
+#endif
 
 	switch (error_code) {
 	case SQFS_ERROR_ALLOC:
@@ -76,4 +89,24 @@ void sqfs_perror(const char *file, const char *action, int error_code)
 		fprintf(stderr, "%s: ", action);
 
 	fprintf(stderr, "%s.\n", errstr);
+
+	if (error_code == SQFS_ERROR_IO) {
+#if defined(_WIN32) || defined(__WINDOWS__)
+		LPVOID msg = NULL;
+
+		FormatMessageA(FORMAT_MESSAGE_ALLOCATE_BUFFER |
+			       FORMAT_MESSAGE_FROM_SYSTEM |
+			       FORMAT_MESSAGE_IGNORE_INSERTS,
+			       NULL, syserror,
+			       MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
+			       (LPTSTR)&msg, 0, NULL);
+
+		fprintf(stderr, "OS error: %s\n", (const char *)msg);
+
+		if (msg != NULL)
+			LocalFree(msg);
+#else
+		fprintf(stderr, "OS error: %s\n", strerror(syserror));
+#endif
+	}
 }