1 files changed, 129 insertions, 0 deletions
diff --git a/kexec/zlib.c b/kexec/zlib.c
new file mode 100644
index 0000000..3ed6bd6
--- /dev/null
+++ b/kexec/zlib.c
@@ -0,0 +1,129 @@
+#include "kexec-zlib.h"
+#include "kexec.h"
+
+#ifdef HAVE_LIBZ
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <stdarg.h>
+#include <string.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <limits.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <ctype.h>
+#include <zlib.h>
+
+static void _gzerror(gzFile fp, int *errnum, const char **errmsg)
+{
+	*errmsg = gzerror(fp, errnum);
+	if (*errnum == Z_ERRNO) {
+		*errmsg = strerror(*errnum);
+	}
+}
+
+int is_zlib_file(const char *filename, off_t *r_size)
+{
+	gzFile fp;
+	int errnum;
+	int is_zlib_file = 0; /* default: It's not in gzip format */
+	const char *msg;
+	ssize_t result;
+
+	if (!filename)
+		goto out;
+
+	fp = gzopen(filename, "rb");
+	if (fp == 0) {
+		_gzerror(fp, &errnum, &msg);
+		dbgprintf("Cannot open `%s': %s\n", filename, msg);
+		goto out;
+	}
+
+	if (!gzdirect(fp))
+		/* It's in gzip format */
+		is_zlib_file = 1;
+
+	result = gzclose(fp);
+	if (result != Z_OK) {
+		_gzerror(fp, &errnum, &msg);
+		dbgprintf(" Close of %s failed: %s\n", filename, msg);
+	}
+
+out:
+	return is_zlib_file;
+}
+
+char *zlib_decompress_file(const char *filename, off_t *r_size)
+{
+	gzFile fp;
+	int errnum;
+	const char *msg;
+	char *buf = NULL;
+	off_t size = 0, allocated;
+	ssize_t result;
+
+	dbgprintf("Try gzip decompression.\n");
+
+	*r_size = 0;
+	if (!filename) {
+		return NULL;
+	}
+	fp = gzopen(filename, "rb");
+	if (fp == 0) {
+		_gzerror(fp, &errnum, &msg);
+		dbgprintf("Cannot open `%s': %s\n", filename, msg);
+		return NULL;
+	}
+	if (gzdirect(fp)) {
+		/* It's not in gzip format */
+		goto fail;
+	}
+	allocated = 65536;
+	buf = xmalloc(allocated);
+	do {
+		if (size == allocated) {
+			allocated <<= 1;
+			buf = xrealloc(buf, allocated);
+		}
+		result = gzread(fp, buf + size, allocated - size);
+		if (result < 0) {
+			if ((errno == EINTR) || (errno == EAGAIN))
+				continue;
+			_gzerror(fp, &errnum, &msg);
+			dbgprintf("Read on %s of %d bytes failed: %s\n",
+				  filename, (int)(allocated - size), msg);
+			size = 0;
+			goto fail;
+		}
+		size += result;
+	} while(result > 0);
+
+fail:
+	result = gzclose(fp);
+	if (result != Z_OK) {
+		_gzerror(fp, &errnum, &msg);
+		dbgprintf(" Close of %s failed: %s\n", filename, msg);
+	}
+
+	if (size > 0) {
+		*r_size = size;
+	} else {
+		free(buf);
+		buf = NULL;
+	}
+	return buf;
+}
+#else
+
+int is_zlib_file(const char *filename, off_t *r_size)
+{
+	return 0;
+}
+
+char *zlib_decompress_file(const char *UNUSED(filename), off_t *UNUSED(r_size))
+{
+	return NULL;
+}
+#endif /* HAVE_ZLIB */