Question

I have following (reduced) simple application which was built with line:

gcc -I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include -D_GNU_SOURCE      -D_XOPEN_SOURCE -std=c99 -ggdb -O0 main-test.c -L/usr/lib -lm -lglib-2.0 -o main-test

The application itself:

#include <stdio.h>
#include <ctype.h>
#include <alloca.h>
#include <glib.h>
#include <glib/gprintf.h>
#include "main.h"

const char *filter(char *original, pt_search_key key) {
    const char *mname = "ModelName";
    const char *pname = "Product";
    const char *delim = " \t";
    const char *delim_str = "\"";
    const char *end = "\n";
    char *value = NULL;
    char *token;
    char *copied = malloc(sizeof(original)+1);
    strcpy(copied, original);

    // Just delete initial tabs and whitespaces
    while(isblank(*copied)) {
        copied++;
        continue;
    }

    token = strsep(&copied, delim);
    if (!strcmp(token, mname))
    {
        token = strsep(&copied, delim_str);
        if(!strcmp(token, "")) {
            token = strsep(&copied, delim_str);

            printf("[before] Token: %s\n", token);
            printf("[before] Value: %s\n", value);
            //*********** Strange behaviour is here!!! *****//
            value = malloc(strlen(token)+1);
            printf("[after] Token: %s\n", token);
            printf("[after] Value: %s\n", value);

            strcpy(value, token);
            token = strsep(&copied, end);
            while(*token != '\0') {
                if(isblank(*token)) {
                    token++;
                    continue;
                } else {
                    printf("String contains unexpected symbols:\n");
                    printf("%s\n", original);
                    exit(EXIT_FAILURE);
                }
           }
        } else {
              printf("String which contains %s is not correct", original);
              exit(EXIT_FAILURE);
        }
    }
return value;
}

int main(int argc, char **argv)
{
    filter("  ModelName \"Business Inkjet 1000\"\n", PT_MODELNAME);
    return EXIT_SUCCESS;
}

This application gives following results:

./main-test 
[before] Token: Business Inkjet 1000
[before] Value: (null)
[after] Token: Business In!
[after] Value: 0

I completely misunderstand why token has been changed. For me output of token should be: "Business Inkjet 1000". Where is error?

Answer 1

I think this is only a typo, but sizeof(original) is only the size of the pointer in this case.

  char *copied = malloc(sizeof(original)+1);   ??

You need:

  char *copied = malloc(strlen(original)+1);