filename.c

#include "filename.h"
 
#include <assert.h>
#include <inttypes.h>
#include <stdio.h>
#include <string.h>
#include <stdint.h>
#include <stddef.h>
#include <stdlib.h>
 
void str_copy(
    char *restrict dst, const ptrdiff_t dst_max, size_t *dst_offset,
    const char *restrict src, const ptrdiff_t src_max, size_t *src_offset,
    const char delim
) {
    const size_t d = dst_offset ? *dst_offset : 0;
    const size_t s = src_offset ? *src_offset : 0;
 
    size_t i;
    for (i = 0; (ptrdiff_t)(i + s) < src_max && src[i + s] && src[i + s] != delim; i++)
        if ((ptrdiff_t)(i + d) < dst_max) dst[i + d] = src[i + s];
 
    if (dst_offset) *dst_offset = d + i;
    if (src_offset) *src_offset = s + i;
}

size_t filename_make(
    char filename[REGION_FILENAME_MAX + 1],
    const char prefix[PREFIX_MAX],
    const char *extension,
    const int64_t *pos, const uint8_t dims
) {
    assert(dims <= CLOD_REGION_DIMENSIONS_MAX);
    memset(filename, 0, REGION_FILENAME_MAX + 1);
 
    size_t offset = 0;
    str_copy(filename, REGION_FILENAME_MAX, &offset, prefix, CLOD_REGION_PREFIX_MAX, nullptr, '.');
    str_copy(filename, REGION_FILENAME_MAX, &offset, ".", 1, nullptr, 0);
 
    for (int i = 0; i < dims; i++) {
        const size_t max_len = offset > REGION_FILENAME_MAX ? 0 : REGION_FILENAME_MAX - offset;
        char *cursor = offset > REGION_FILENAME_MAX ? filename + REGION_FILENAME_MAX : filename + offset;
        offset += (size_t)snprintf(cursor, max_len, "%"PRId64".", pos[i]);
    }
 
    str_copy(filename, REGION_FILENAME_MAX, &offset, extension, EXTENSION_MAX, nullptr, 0);
    assert(offset <= REGION_FILENAME_MAX);
    return offset;
}

bool filename_parse_pos(const char filename[REGION_FILENAME_MAX + 1],
                      const char prefix[PREFIX_MAX],
                      const char *extension,
                      int64_t *pos, const uint8_t dims
) {
    size_t offset = 0;
    while (offset < PREFIX_MAX && prefix[offset]) {
        if (prefix[offset] != filename[offset]) return false;
        offset++;
    }
 
    if (filename[offset] != '.') return false;
    offset++;
 
    for (uint8_t i = 0; i < dims; i++) {
        char *end;
        pos[i] = strtoll(&filename[offset], &end, 10);
        if (end == filename + offset) return false;
        offset += (size_t)(end - filename) + 1;
    }
 
    size_t extension_offset = 0;
    while (extension_offset < EXTENSION_MAX && extension[extension_offset]) {
        if (extension[extension_offset] != filename[offset]) return false;
        extension_offset++;
        offset++;
    }
 
    if (filename[offset]) return false;
    return true;
}