util: Let callers pass an offset to read_file

When reading from a dump file, read_file would be more convenient to
use than mem_chunk, but it lacks an offset parameter.

Signed-off-by: Jean Delvare <[email protected]>

Author: jdelvare

CHANGELOG

@@ -1,6 +1,8 @@
 2017-04-11  Jean Delvare  <[email protected]>
 
 	* util.c: Don't leak a file descriptor in function read_file.
+	* util.c, util.c, dmidecode.c: Let callers pass an offset to function
+	  read_file.
 
 2017-04-10  Jean Delvare  <[email protected]>
 

dmidecode.c

@@ -4550,7 +4550,7 @@ static void dmi_table(off_t base, u32 len, u16 num, u16 ver, const char *devmem,
 		 * result of the kernel truncating the table on parse error.
 		 */
 		size_t size = len;
-		buf = read_file(&size, devmem);
+		buf = read_file(0, &size, devmem);
 		if (!(opt.flags & FLAG_QUIET) && num && size != (size_t)len)
 		{
 			fprintf(stderr, "Wrong DMI structures length: %u bytes "
@@ -4862,7 +4862,7 @@ int main(int argc, char * const argv[])
 	 */
 	size = 0x20;
 	if (!(opt.flags & FLAG_NO_SYSFS)
-	 && (buf = read_file(&size, SYS_ENTRY_FILE)) != NULL)
+	 && (buf = read_file(0, &size, SYS_ENTRY_FILE)) != NULL)
 	{
 		if (!(opt.flags & FLAG_QUIET))
 			printf("Getting SMBIOS data from sysfs.\n");

util.c

@@ -2,7 +2,7 @@
  * Common "util" functions
  * This file is part of the dmidecode project.
  *
- *   Copyright (C) 2002-2015 Jean Delvare <[email protected]>
+ *   Copyright (C) 2002-2017 Jean Delvare <[email protected]>
  *
  *   This program is free software; you can redistribute it and/or modify
  *   it under the terms of the GNU General Public License as published by
@@ -89,7 +89,7 @@ int checksum(const u8 *buf, size_t len)
 }
 
 /*
- * Reads all of file, up to max_len bytes.
+ * Reads all of file from given offset, up to max_len bytes.
  * A buffer of max_len bytes is allocated by this function, and
  * needs to be freed by the caller.
  * This provides a similar usage model to mem_chunk()
@@ -98,7 +98,7 @@ int checksum(const u8 *buf, size_t len)
  * sets max_len to the length actually read.
  *
  */
-void *read_file(size_t *max_len, const char *filename)
+void *read_file(off_t base, size_t *max_len, const char *filename)
 {
 	int fd;
 	size_t r2 = 0;
@@ -116,6 +116,14 @@ void *read_file(size_t *max_len, const char *filename)
 		return NULL;
 	}
 
+	if (lseek(fd, base, SEEK_SET) == -1)
+	{
+		fprintf(stderr, "%s: ", filename);
+		perror("lseek");
+		p = NULL;
+		goto out;
+	}
+
 	if ((p = malloc(*max_len)) == NULL)
 	{
 		perror("malloc");

util.h

@@ -1,7 +1,7 @@
 /*
  * This file is part of the dmidecode project.
  *
- *   Copyright (C) 2003-2015 Jean Delvare <[email protected]>
+ *   Copyright (C) 2003-2017 Jean Delvare <[email protected]>
  *
  *   This program is free software; you can redistribute it and/or modify
  *   it under the terms of the GNU General Public License as published by
@@ -25,7 +25,7 @@
 #define ARRAY_SIZE(x) (sizeof(x)/sizeof((x)[0]))
 
 int checksum(const u8 *buf, size_t len);
-void *read_file(size_t *len, const char *filename);
+void *read_file(off_t base, size_t *len, const char *filename);
 void *mem_chunk(off_t base, size_t len, const char *devmem);
 int write_dump(size_t base, size_t len, const void *data, const char *dumpfile, int add);
 u64 u64_range(u64 start, u64 end);