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

diff --git a/modutils/modprobe.c b/modutils/modprobe.c
index a72028fa2807a26929f2f77d80f3c51b4e2dd8e7..fbe18b640b85919f0246598d0544bafc70bbb675 100644 (file)
--- 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;