strip_pipe_delimited_fields.c

#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

static char * append (char *field, size_t *size, size_t *len, char c);
static size_t get_field (char **field, size_t *size, FILE *file);
static char const * strip_field (char *field, size_t len);

static bool end_of_file = false;
static bool end_of_line;

int
main (int argc, char *argv [])
{
    char       *field = NULL;
    FILE       *file;
    char const *filename;
    size_t      len;
    size_t      size = 0;
    char const *stripped;

    if (2 != argc) {
        printf("Exactly one filename must be specified\n");
        return EXIT_FAILURE;
    }

    filename = argv[1];
    file = fopen(filename, "r");
    if (NULL == file) {
        printf("%s: file not found\n", filename);
        return EXIT_FAILURE;
    }

NEW_LINE:
    len = get_field(&field, &size, file);
    stripped = strip_field(field, len);
    if (strcmp("", stripped)) {
        printf("%s", stripped);
        if (end_of_file) {
            goto EXIT;
        }
    } else {
        if (end_of_file) {
            goto EXIT;
        }
        printf("null");
    }

    while (!end_of_line) {
        len = get_field(&field, &size, file);
        printf("|%s", strip_field(field, len));
        if (end_of_file) {
            goto EXIT;
        }
    }

    printf("\n");
    goto NEW_LINE;

EXIT:
    free(field);

    fclose(file);

    return EXIT_SUCCESS;
}

char *
append (char *field, size_t *size, size_t *len, char c)
{
    if (*size <= (*len + 1)) {
        field = (char *)realloc(field, *size + 64);
        *size += 64;
    }

    field[(*len)++] = c;

    return field;
}

size_t
get_field (char **field, size_t *size, FILE *file)
{
    int    c;
    size_t len = 0;

    end_of_line = false;
    c = fgetc(file);
    while ('|' != c) {
        if ('\n' == c) {
            end_of_line = true;
            goto EXIT;
        }
        if (EOF == c) {
            end_of_file = true;
            goto EXIT;
        }
        *field = append(*field, size, &len, c);
        c = fgetc(file);
    }

EXIT:
    (*field)[len] = '\0';

    return len;
}

char const *
strip_field (char *field, size_t len)
{
    size_t b;
    size_t e;

    if (0 == len) {
        return field;
    }

    for (b = 0; b < len; ++b) {
        if ((' ' != field[b]) && ('\t' != field[b])) {
            break;
        }
    }

    for (e = len - 1; e > b; --e) {
        if ((' ' != field[e]) && ('\t' != field[e])) {
            break;
        }
    }

    if (e == b) {
        field[b] = '\0';
    } else {
        field[e + 1] = '\0';
    }

    return field + b;
}

// Local Variables:
// c-basic-offset: 4
// indent-tabs-mode: nil
// End:

// vi: set et ts=4 sw=4 :