From f64c3f549eda36d11b5690117173b0847535ebbe Mon Sep 17 00:00:00 2001
From: Takashi Iwai <tiwai@suse.de>
Date: Mon, 24 Aug 2020 14:40:17 +0200
Subject: [PATCH] Add buffer read helper using read explicitly

Since mmap can't work well with a sysfs file, we need to read the
contents explicitly via read, even if USE_MMAP is enabled.
Provide a new helper, __mem_cunk(), that does behave like mem_chunk()
but with the extra use_mmap argument to specify the method to read a
file.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
CC: Thomas Renninger <trenn@suse.de>
CC: Michal Suchanek <msuchanek@suse.com>
---
 src/dmidecode/util.c | 82 ++++++++++++++++++++++++++++----------------
 src/dmidecode/util.h |  1 +
 2 files changed, 53 insertions(+), 30 deletions(-)

diff --git a/src/dmidecode/util.c b/src/dmidecode/util.c
index ea06663..09934ea 100644
--- a/src/dmidecode/util.c
+++ b/src/dmidecode/util.c
@@ -47,7 +47,6 @@
 #include "types.h"
 #include "util.h"
 
-#ifndef USE_MMAP
 static int myread(int fd, u8 *buf, size_t count, const char *prefix)
 {
 	ssize_t r=1;
@@ -78,7 +77,6 @@ static int myread(int fd, u8 *buf, size_t count, const char *prefix)
 	
 	return 0;
 }
-#endif
 
 int checksum(const u8 *buf, size_t len)
 {
@@ -94,28 +92,13 @@ int checksum(const u8 *buf, size_t len)
  * Copy a physical memory chunk into a memory buffer.
  * This function allocates memory.
  */
-void *mem_chunk(size_t base, size_t len, const char *devmem)
-{
-	void *p;
-	int fd;
 #ifdef USE_MMAP
+static void *mem_chunk_mmap(size_t base, size_t len, const char *devmem,
+			    int fd, void *p)
+{
 	size_t mmoffset;
 	void *mmp;
-#endif
-	
-	if((fd=open(devmem, O_RDONLY))==-1)
-	{
-		return NULL;
-	}
-	
-	if((p=malloc(len))==NULL)
-	{
-		perror("malloc");
-		close(fd);
-		return NULL;
-	}
-	
-#ifdef USE_MMAP
+
 #ifdef _SC_PAGESIZE
 	mmoffset=base%sysconf(_SC_PAGESIZE);
 #else
@@ -129,8 +112,6 @@ void *mem_chunk(size_t base, size_t len, const char *devmem)
 	mmp=mmap(0, mmoffset+len, PROT_READ, MAP_SHARED, fd, base-mmoffset);
 	if(mmp==MAP_FAILED)
 	{
-		free(p);
-		close(fd);
 		return NULL;
 	}
 	
@@ -141,26 +122,67 @@ void *mem_chunk(size_t base, size_t len, const char *devmem)
 		fprintf(stderr, "%s: ", devmem);
 		perror("munmap");
 	}
-#else /* USE_MMAP */
+
+	return p;
+}
+#endif /* USE_MMAP */
+
+static void *mem_chunk_read(size_t base, size_t len, const char *devmem,
+			    int fd, void *p)
+{
 	if(lseek(fd, base, SEEK_SET)==-1)
 	{
 		fprintf(stderr, "%s: ", devmem);
 		perror("lseek");
-		free(p);
-		close(fd);
 		return NULL;
 	}
 	
 	if(myread(fd, p, len, devmem)==-1)
 	{
-		free(p);
-		close(fd);
 		return NULL;
 	}
-#endif /* USE_MMAP */
+
+	return p;
+}
+
+void *__mem_chunk(size_t base, size_t len, const char *devmem, int use_mmap)
+{
+	void *ret;
+	void *p;
+	int fd;
+
+#ifndef USE_MMAP
+	use_mmap = 0;
+#endif
+
+	if((fd=open(devmem, O_RDONLY))==-1)
+	{
+		return NULL;
+	}
 	
+	if((p=malloc(len))==NULL)
+	{
+		perror("malloc");
+		close(fd);
+		return NULL;
+	}
+
+#ifdef USE_MMAP
+	if (use_mmap)
+		ret = mem_chunk_mmap(base, len, devmem, fd, p);
+	else
+#endif
+		ret = mem_chunk_read(base, len, devmem, fd, p);
+
 	if(close(fd)==-1)
 		perror(devmem);
+	if (!ret)
+		free(p);
 
-	return p;
+	return ret;
+}
+
+void *mem_chunk(size_t base, size_t len, const char *devmem)
+{
+	return __mem_chunk(base, len, devmem, 1);
 }
diff --git a/src/dmidecode/util.h b/src/dmidecode/util.h
index b546f64..90c411e 100644
--- a/src/dmidecode/util.h
+++ b/src/dmidecode/util.h
@@ -6,3 +6,4 @@
 
 int checksum(const u8 *buf, size_t len);
 void *mem_chunk(size_t base, size_t len, const char *devmem);
+void *__mem_chunk(size_t base, size_t len, const char *devmem, int use_mmap);
-- 
2.44.0