quote-bot/io.c

#include <assert.h>             /* assert */
#include <stdio.h>              /* FILE* */
#include <stdlib.h>             /* malloc, free */
#include <unistd.h>             /* unlink */

#include "io.h"

/* <https://rosettacode.org/wiki/Read_entire_file#C> */
char *file_read(const char *filename, size_t *readSize) {
    char *buffer;
    FILE *fh;
    long size;
    size_t nread;
    assert(filename != NULL);
    buffer = NULL;
    fh = fopen(filename, "rb");
    if (fh != NULL) {
        fseek(fh, 0L, SEEK_END);
        size = ftell(fh);
        rewind(fh);
        if (size > 0)
            buffer = (char *)malloc((size_t)size);
        if (buffer != NULL) {
            assert(buffer != NULL);
            nread = fread(buffer, 1, (size_t)size, fh);
            fclose(fh);
            fh = NULL;
            if (size != (long)nread) {
                free(buffer);
                buffer = NULL;
            }
            assert(size == (long)nread);
            if (NULL != readSize) {
                *readSize = nread;
            }
        }
        if (fh != NULL)
            fclose(fh);
    }
    return buffer;
}

/* <https://www.rosettacode.org/wiki/Write_entire_file#C> */
size_t file_write(const char *fileName, const void *data, const size_t size) {
    size_t numberBytesWritten = 0;
    FILE *file;
    assert(fileName != NULL);
    assert(data != NULL);
    assert(size > 0);
    if (fileName != NULL && *fileName != '\0') {
        file = fopen(fileName, "wb");
        if (file != NULL) {
            if (data != NULL) {
                numberBytesWritten = fwrite(data, 1, size, file);
            }
            fclose(file);
        }
    }
    return numberBytesWritten;
}

int copy_file(const char *srcname, const char *dstname) {
    int rc;
    char *buf;
    size_t nread, nwrite;
    rc = -1;
    buf = file_read(srcname, &nread);
    if (buf) {
        nwrite = file_write(dstname, buf, nread);
        if (nread != nwrite) {
            fprintf(stderr, "Incorrect write size (%ld != %ld)\n", nread, nwrite);
            unlink(dstname);
        }
        assert(nread == nwrite);
        free(buf);
        rc = 0;
    }
    return rc;
}