Question

So I am having trouble implementing the mtime struct in C, where I am trying to check the last modification time of a file. When compiling, I receive this error:

pr8.1.c:246: error: incompatible types when assigning to type struct timespec from type time_t
make: *** [pr8] Error 1

The code I am using for this is as follows:

static struct timespec mtime(const char *file)
{
    struct stat s;
    struct timespec t = { 0, 0 };

    if (stat(file, &s) == 0)
#if     defined(MTIME) && MTIME == 1    // Linux
    { t = s.st_mtime; }
#elif   defined(MTIME) && MTIME == 2    // Mac OS X
    { t = s.st_mtimespec; }
#elif   defined(MTIME) && MTIME == 3    // Mac OS X, with some additional settings
    { t.tv_sec = s.st_mtime; t.tv_nsec = s.st_mtimensec; }
#else                                   // Solaris
    { t.tv_sec = s.st_mtime; }
#endif

    return t;
}

And the struct stat:

struct stat
{ time_t        st_mtime; };

P.S. sorry about the format, I am not sure why the format is acting like this. Running this with Linux. Thanks in advance for the help.

Answer 1

In the linux and first mac os x version, you’re assigning to the structure from an int (time_t). In the other two versions, you are correctly assigning from a member of s to a member of t. If you change to this, do you get correct operation?

static struct timespec mtime(const char *file)
{
    struct stat s;
    struct timespec t = { 0, 0 };

    if (stat(file, &s) == 0)
#if     defined(MTIME) && MTIME == 1    // Linux
    { t.tv_sec = s.st_mtime; }
//     ^^^^^^^ 
#elif   defined(MTIME) && MTIME == 2    // Mac OS X
    { t.tv_sec = s.st_mtimespec; }
//     ^^^^^^^ 
#elif   defined(MTIME) && MTIME == 3    // Mac OS X, with some additional settings
    { t.tv_sec = s.st_mtime; t.tv_nsec = s.st_mtimensec; }
#else                                   // Solaris
    { t.tv_sec = s.st_mtime; }
#endif

    return t;
}