Parse a substring out of string, allocate memory accordingly

Question

I have written the following code in order to:

1. Find begin and end of FTP user and password from a given URL (ftp://[user[:password]@]host[:port]/url-path)
2. Allocate memory to hold this string
3. Copy the sub-string into the allocated memory

Here is the code for your review:

static char * swd_parseUsrPass(void)
{
 char *usr_pass = NULL;
 char *url_str = NULL;
 char *beginIndx = NULL;
 char *endIndx = NULL;
 int str_len = 0;
 url_str = getURLaddr();
 /* Find begin and end indexs */
 beginIndx = url_str + strlen(FTP_PREFIX);
 endIndx = strchr(beginIndx, '@');
 if ((endIndx == NULL) || endIndx <= beginIndx) {
 printf("Could not locate user and password in URL\n");
 return NULL;
 }
 str_len = endIndx - beginIndx;
 /* Allocate maximum possible string */
 usr_pass = malloc((sizeof(char) * str_len) + 1);
 if (usr_pass == NULL) {
 printf("Failed to allocated memory!\n");
 return NULL;
 }
 /* Copy user and password to new string */
 strncpy(usr_pass, beginIndx, str_len);
 *(endIndx + 1) = '0円';
 return usr_pass;
}

• Loki Astari: Though not common. The @ character can appear in the url-path
• Loki Astari: Also if this was going to go into real code. You have to remember that on the web URL don't always follow spec (as a writer of a web crawler I can testify to the number of badly written URLS). So the '/' marking the url-path may not be there so you have to check for all the common mistakes. ? , & , # , :

Answer 1

• A 0-ary function (swd_parseUsrPass) calling another 0-ary function (swd_getURLaddr) hints that there are global variables lurking around. Using globals is not recommended; if they are unavoidable, at least limit their visibility. Consider char swd_parseUsrPass(char * url_addr), and let the caller provide the argument.

• sizeof(char) is guaranteed to be 1.

• *(endIndx + 1) = '0円' modifies the source string, while usr_pass remains not terminated. I presume you meant

  usr_pass[str_len] = '0円';
  

• dear_tzvi: Thank you @vnp. I'm actually not using global variables, but I do use static variables (defined only in this C file content) - do you see any problem with that?

Answer 2

I agree with all points made by vnp, except I'd suggest swd_parseUsrPass(const char *url_addr) as the prototype, and I'd add:

• all your pointers except usr_pass should be const char * as you do not intend to modify the string they point to. This would have help you noticing the *(endIndx + 1) = '0円' issue pointed out by vnp.
• the test endIndx <= beginIndx seems redundant to me
• I'm not a big fan of Indx in the name: these are pointers, indexes would be integers (not a big fan of mixing underscores and camelCase either, but that's more an issue of taste)