Cleaned up Erik's fgets -> read patch and fixed a buffer overflow

1 files changed, 38 insertions, 36 deletions

diff --git a/modutils/modprobe.c b/modutils/modprobe.c
index a72028fa2..fbe18b640 100644
--- a/modutils/modprobe.c
+++ b/modutils/modprobe.c
@@ -44,9 +44,38 @@ static struct dep_t *depend;
 static int autoclean, show_only, quiet, do_syslog, verbose;
 
 
+/* Jump through hoops to simulate how fgets() grabs just one line at a
+ * time... Don't use any stdio since modprobe gets called from a kernel
+ * thread and stdio junk can overflow the limited stack... 
+ */
+static char *reads ( int fd, char *buffer, size_t len )
+{
+        int n = read ( fd, buffer, len );
+        
+        if ( n > 0 ) {
+                char *p;
+        
+                buffer [len-1] = 0;
+                p = strchr ( buffer, '\n' );
+                
+                if ( p ) {
+                        off_t offset;
+                        
+                        offset = lseek ( fd, 0L, SEEK_CUR );               // Get the current file descriptor offset 
+                        lseek ( fd, offset-n + (p-buffer) + 1, SEEK_SET ); // Set the file descriptor offset to right after the \n
+
+                        p[1] = 0;
+                }
+                return buffer;
+        }
+        
+        else
+                return 0;
+}
+
 static struct dep_t *build_dep ( void )
 {
-        int fd, n;
+        int fd;
         struct utsname un;
         struct dep_t *first = 0;
         struct dep_t *current = 0;
@@ -66,27 +95,13 @@ static struct dep_t *build_dep ( void )
         strcat ( filename, un.release );
         strcat ( filename, "/modules.dep" );
 
-        if ((fd = open ( filename, O_RDONLY )) < 0)
+        if (( fd = open ( filename, O_RDONLY )) < 0 )
                 return 0;
 
-        while ( (n = read(fd, buffer, 255)) > 0) {
-                int l;
+        while ( reads ( fd, buffer, sizeof( buffer ))) {
+                int l = xstrlen ( buffer );
                 char *p = 0;
-
-                /* Jump through hoops to simulate how fgets() grabs just one line at a
-                 * time... Don't use any stdio since modprobe gets called from a kernel
-                 * thread and stdio junk can overflow the limited stack... */
-                p = strchr ( buffer, '\n' );
-                if (p) {
-                        off_t offset;
-                        /* Get the current file descriptor offset */
-                        offset = lseek(fd, 0L, SEEK_CUR);
-                        /* Set the file descriptor offset to right after the \n */
-                        lseek(fd, offset-n+p-buffer+1, SEEK_SET);
-                        *(p+1)='\0';
-                }
-
-                l = xstrlen ( buffer );
+                
                 while ( isspace ( buffer [l-1] )) {
                         buffer [l-1] = 0;
                         l--;
@@ -182,29 +197,16 @@ static struct dep_t *build_dep ( void )
 
         // alias parsing is not 100% correct (no correct handling of continuation lines within an alias) !
 
-        if ((fd = open ( "/etc/modules.conf", O_RDONLY )) < 0)
-                if ((fd = open ( "/etc/conf.modules", O_RDONLY )) < 0)
+        if (( fd = open ( "/etc/modules.conf", O_RDONLY )) < 0 )
+                if (( fd = open ( "/etc/conf.modules", O_RDONLY )) < 0 )
                         return first;
         
         continuation_line = 0;
-        while ( read(fd, buffer, 255) > 0) {
+        while ( reads ( fd, buffer, sizeof( buffer ))) {
                 int l;
                 char *p;
                 
-                /* Jump through hoops to simulate how fgets() grabs just one line at a
-                 * time... Don't use any stdio since modprobe gets called from a kernel
-                 * thread and stdio junk can overflow the limited stack... */
-                p = strchr ( buffer, '\n' );
-                if (p) {
-                        off_t offset;
-                        /* Get the current file descriptor offset */
-                        offset = lseek(fd, 0L, SEEK_CUR);
-                        /* Set the file descriptor offset to right after the \n */
-                        lseek(fd, offset-n+p-buffer+1, SEEK_SET);
-                        *(p+1)='\0';
-                }
-
-                p = strchr ( buffer, '#' );
+                p = strchr ( buffer, '#' );     
                 if ( p )
                         *p = 0;