My intention was to open two files, where the second one would be brand new, with the same permissions as the first file. So to test my code I changed the first file permissions to "777". Then I proceeded to run my program. And to my surprise, the permission of the newborn file2 were wrong! They where set to 755. Even weirder is when I set the first file to "111" and tried again, the result now was "1204". Can someone explain to me this weird behavior?
Here's my code
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
int main(int argc, char *args[]) {
struct stat stats;
int fd1, fd2;
fd1 = open("testfile.txt", O_RDONLY);
/* Error check*/
if (fd1 == -1) {
/* Error handling */
perror("Opening");
printf("Unable to open file: %s\n", "testfile.txt");
printf("ERROR: %s\n", strerror(errno));
return 1;
}
if(fstat(fd1, &stats) == -1)
{
printf("Error while getting stats: %s\n", strerror(errno));
exit(-1);
}
//Receives the output file as a main argument . . .
if (argc > 1)
{
//(stats.st_mode = Gets the mask of the first file)
fd2 = open(args[1], O_WRONLY|O_CREAT, stats.st_mode);
/* Error check*/
if (fd2 == -1) {
/* Error handling */
perror("Opening");
printf("Unable to open file: %s\n",args[1]);
printf("ERROR: %s\n", strerror(errno));
return 1;
}
}
//. . . if it doesn't it creates a standard one warning you about it
else
{
fd2 = open("Nope.txt", O_WRONLY|O_CREAT, stats.st_mode);
/* Error check*/
if (fd2 == -1) {
/* Error handling */
perror("Opening");
printf("Unable to open file: %s\n",args[1]);
printf("ERROR: %s\n", strerror(errno));
return 1;
}
printf("Standard file created\n");
}
close(fd1);
close(fd2);
return 0;
}
I tried to make it as tidy as I could :)
