lib/get_num.c

This is lib/get_num.c (Listing 3-6, page 59), an example from the book, The Linux Programming Interface.

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Download lib/get_num.c

Cover of The Linux Programming Interface

Function list (Bold in this list means a function is not static)

gnFail()
getNum()
getLong()
getInt()

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <limits.h>
#include <errno.h>
#include "get_num.h"

static void
gnFail(const char *fname, const char *msg, const char *arg, const char *name)
{
    fprintf(stderr, "%s error", fname);
    if (name != NULL)
        fprintf(stderr, " (in %s)", name);
    fprintf(stderr, ": %s\n", msg);
    if (arg != NULL && *arg != '\0')
        fprintf(stderr, "        offending text: %s\n", arg);

    exit(EXIT_FAILURE);
}

static long
getNum(const char *fname, const char *arg, int flags, const char *name)
{
    long res;
    char *endptr;
    int base;

    if (arg == NULL || *arg == '\0')
        gnFail(fname, "null or empty string", arg, name);

    base = (flags & GN_ANY_BASE) ? 0 : (flags & GN_BASE_8) ? 8 :
                        (flags & GN_BASE_16) ? 16 : 10;

    errno = 0;
    res = strtol(arg, &endptr, base);
    if (errno != 0)
        gnFail(fname, "strtol() failed", arg, name);

    if (*endptr != '\0')
        gnFail(fname, "nonnumeric characters", arg, name);

    if ((flags & GN_NONNEG) && res < 0)
        gnFail(fname, "negative value not allowed", arg, name);

    if ((flags & GN_GT_0) && res <= 0)
        gnFail(fname, "value must be > 0", arg, name);

    return res;
}

long
getLong(const char *arg, int flags, const char *name)
{
    return getNum("getLong", arg, flags, name);
}

int
getInt(const char *arg, int flags, const char *name)
{
    long res;

    res = getNum("getInt", arg, flags, name);

    if (res > INT_MAX || res < INT_MIN)
        gnFail("getInt", "integer out of range", arg, name);

    return res;
}

Download lib/get_num.c

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