Clean comment for mymount.c (simple wrapper for mount syscall).

diff --git a/sources/mymount.c b/sources/mymount.c
index 9c8da0d423d3eb81d9c0ddedb1ded75e44804943..c4e31a6daa6cd73880ea7277e6d6d35c303bae27 100644 (file)
--- a/sources/mymount.c
+++ b/sources/mymount.c
@@ -31,15 +31,14 @@
 #include <string.h>
 #include <sys/mount.h>
 
-#ifdef DEBUG                     /* done only on debugging */
+/* pass -D DEBUG to gcc to enable debug printing */
+#ifdef DEBUG
 #define debug printf
 #else
 #define debug(fmt, arg...)
 #endif /* DEBUG */
 
-
 /* Adding undefined flags in glibc headers */ 
-
 #ifndef MS_DIRSYNC      
 #define MS_DIRSYNC 128
 #endif
@@ -81,12 +80,13 @@
 /* Help printing routine */
 void usage(void);
 
+/* struct for name<->flag correspondence */
 struct ms_flag {
     const char *name;
     int flag;
 };
 
-/* compare funtion */
+/* compare funtion to find a flag name */
 int ms_flag_cmp(const void *c1, const void *c2) 
 {
     struct ms_flag *v1 = (struct ms_flag *) c1;
@@ -94,8 +94,7 @@ int ms_flag_cmp(const void *c1, const void *c2)
     return strcmp(v1->name, v2->name);
 }
 
-
-
+/* main body */
 int main(int argc, char *argv[]) 
 {
 /* 
@@ -104,6 +103,7 @@ int main(int argc, char *argv[])
     int i, flags=0;
     char * mountflags=NULL, *data=NULL, *filesystemtype=NULL;
     char *token;
+    /* mount flag table, must be alphabetically ordered */
     struct ms_flag ms_values[]=
        {
            {"bind", MS_BIND},
@@ -135,7 +135,7 @@ int main(int argc, char *argv[])
      * Use getopt function
      */
     opterr = 0;         /* don't want writing to stderr */
-    while ( (i = getopt(argc, argv, "d:f:t:h")) != -1) {
+    while ( (i = getopt(argc, argv, "o:f:t:h")) != -1) {
        switch (i) {
        /* 
         * Handling options 
@@ -145,15 +145,15 @@ int main(int argc, char *argv[])
            usage();
            return -1;
            break;
-        case 'd':                                  /* options data */
+        case 'o':                                  /* options data */
             data = optarg;
            debug("passed option data: %s\n", data);
             break;
-        case 't':                                  /* options data */
+        case 't':                                  /* filesystem type */
             filesystemtype = optarg;
            debug("passed filesystem type: %s\n", filesystemtype);
             break;
-        case 'f':                                  /* options data */ 
+        case 'f':                                  /* mount flags */ 
             mountflags = optarg;
            debug("passed mount flags: %s\n", mountflags);
            break;
@@ -171,14 +171,14 @@ int main(int argc, char *argv[])
      *               Main code beginning
      * 
      * ***********************************************************/
-    if ((argc - optind) != 2) {   /* There must be 0 remaing arguments */
+    /* There must be 2 arguments, source and target */
+    if ((argc - optind) != 2) {   
        printf("Wrong number of arguments %d\n", argc - optind);
         usage();
     }
     debug("source %s, target %s\n",argv[optind], argv[optind+1]);
-    
-//    printf("\n",);
 
+    /* parse -f option parameter, and build mount flags argument */ 
     if ( token = strtok(mountflags, ",") ) {
         do {
            key.name = token;
@@ -194,6 +194,7 @@ int main(int argc, char *argv[])
        } while (token=strtok(NULL,","));
     }
     debug("flags value %X\n", flags);
+    /* do mount */
     if (mount(argv[optind], argv[optind + 1], filesystemtype, flags, data) == -1) {
        perror("Mount call failed");
        exit(EXIT_FAILURE);
@@ -206,10 +207,14 @@ int main(int argc, char *argv[])
 void usage(void) {
     printf("Program mymount:  \n");
     printf("Usage:\n");
-    printf("mymount [-h] [-d opt1[,...]] [-t type] [-f fl1[,...]] source target\n");
+    printf("mymount [-h] [-o opt1[,...]] [-t type] [-f fl1[,...]] source target\n");
     printf("  -h          print this help\n");
-    printf("  -d options  comma separated options data string\n");
+    printf("  -o options  comma separated options data string\n");
     printf("  -t fstype   filesystemtype string\n");
-    printf("  -f flags     comma separated mount flags string\n");
+    printf("  -f flags    comma separated mount flags string\n");
+    printf("\n");
+    printf("you always need to specify two argument, source and target,\n");
+    printf("matching the system call ones, if one of them is not needed\n");
+    printf("just pass an empty string\n");
     exit(1);
 }