From ae1d534074286bb6c206a13b7b07503ee458396a Mon Sep 17 00:00:00 2001
From: smitsohu <smitsohu@gmail.com>
Date: Sat, 13 Mar 2021 21:20:38 +0100
Subject: appimage: calculate elf offset from file descriptor

---
 src/firejail/appimage.c      |  2 +-
 src/firejail/appimage_size.c | 22 ++++++++--------------
 src/firejail/firejail.h      |  2 +-
 3 files changed, 10 insertions(+), 16 deletions(-)

diff --git a/src/firejail/appimage.c b/src/firejail/appimage.c
index cc66608d3..59758bf2d 100644
--- a/src/firejail/appimage.c
+++ b/src/firejail/appimage.c
@@ -61,7 +61,7 @@ void appimage_set(const char *appimage) {
 
 	// get appimage type and ELF size
 	// a value of 0 means we are dealing with a type1 appimage
-	size = appimage2_size(appimage);
+	size = appimage2_size(ffd);
 	if (arg_debug)
 		printf("AppImage ELF size %lu\n", size);
 
diff --git a/src/firejail/appimage_size.c b/src/firejail/appimage_size.c
index 4640cb8a5..43ca501da 100644
--- a/src/firejail/appimage_size.c
+++ b/src/firejail/appimage_size.c
@@ -132,22 +132,20 @@ static long unsigned int read_elf64(int fd) {
 
 // return 0 if error
 // return 0 if this is not an appimgage2 file
-long unsigned int appimage2_size(const char *fname) {
+long unsigned int appimage2_size(int fd) {
 	ssize_t ret;
-	int fd;
 	long unsigned int size = 0;
 
-	fd = open(fname, O_RDONLY);
 	if (fd < 0)
 		return 0;
 
 	ret = pread(fd, ehdr.e_ident, EI_NIDENT, 0);
 	if (ret != EI_NIDENT)
-		goto getout;
+		return 0;
 
 	if ((ehdr.e_ident[EI_DATA] != ELFDATA2LSB) &&
 	     (ehdr.e_ident[EI_DATA] != ELFDATA2MSB))
-		goto getout;
+		return 0;
 
 	if(ehdr.e_ident[EI_CLASS] == ELFCLASS32) {
 		size = read_elf32(fd);
@@ -156,23 +154,19 @@ long unsigned int appimage2_size(const char *fname) {
 		size = read_elf64(fd);
 	}
 	else {
-		goto getout;
+		return 0;
 	}
 	if (size == 0)
-		goto getout;
+		return 0;
 
 
 	// look for a LZMA header at this location
 	unsigned char buf[4];
 	ret = pread(fd, buf, 4, size);
-	if (ret != 4) {
-		size = 0;
-		goto getout;
-	}
+	if (ret != 4)
+		return 0;
 	if (memcmp(buf, "hsqs", 4) != 0)
-		size = 0;
+		return 0;
 
-getout:
-	close(fd);
 	return size;
 }
diff --git a/src/firejail/firejail.h b/src/firejail/firejail.h
index 3b9a00c3f..ca4c988fa 100644
--- a/src/firejail/firejail.h
+++ b/src/firejail/firejail.h
@@ -802,7 +802,7 @@ void appimage_mount(void);
 void appimage_clear(void);
 
 // appimage_size.c
-long unsigned int appimage2_size(const char *fname);
+long unsigned int appimage2_size(int fd);
 
 // cmdline.c
 void build_cmdline(char **command_line, char **window_title, int argc, char **argv, int index);
-- 
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