wireshark/wsutil/wmem/wmem_strbuf.c

/* wmem_strbuf.c
 * Wireshark Memory Manager String Buffer
 * Copyright 2012, Evan Huus <eapache@gmail.com>
 *
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * Copyright 1998 Gerald Combs
 *
 * SPDX-License-Identifier: GPL-2.0-or-later
 */

#include "config.h"
#include "wmem_strbuf.h"

#include <stdio.h>
#include <errno.h>

#include "wmem-int.h"
#include "wmem_strutl.h"

#include <wsutil/unicode-utils.h>

#define DEFAULT_MINIMUM_SIZE 16

/* _ROOM accounts for the null-terminator, _RAW_ROOM does not.
 * Some functions need one, some functions need the other. */
#define WMEM_STRBUF_ROOM(S) ((S)->alloc_size - (S)->len - 1)
#define WMEM_STRBUF_RAW_ROOM(S) ((S)->alloc_size - (S)->len)

wmem_strbuf_t *
wmem_strbuf_new_sized(wmem_allocator_t *allocator,
                      size_t alloc_size)
{
    wmem_strbuf_t *strbuf;

    strbuf = wmem_new(allocator, wmem_strbuf_t);

    strbuf->allocator = allocator;
    strbuf->len       = 0;
    strbuf->alloc_size = alloc_size ? alloc_size : DEFAULT_MINIMUM_SIZE;

    strbuf->str    = (gchar *)wmem_alloc(strbuf->allocator, strbuf->alloc_size);
    strbuf->str[0] = '\0';

    return strbuf;
}

wmem_strbuf_t *
wmem_strbuf_new_len(wmem_allocator_t *allocator, const gchar *str, size_t len)
{
    wmem_strbuf_t *strbuf;
    size_t          alloc_size;

    alloc_size = DEFAULT_MINIMUM_SIZE;

    /* +1 for the null-terminator */
    while (alloc_size < (len + 1)) {
        alloc_size *= 2;
    }

    strbuf = wmem_strbuf_new_sized(allocator, alloc_size);

    if (str && len > 0) {
        ws_assert(strbuf->alloc_size >= len + 1);
        memcpy(strbuf->str, str, len);
        strbuf->str[len] = '\0';
        strbuf->len = len;
    }

    return strbuf;
}

wmem_strbuf_t *
wmem_strbuf_new(wmem_allocator_t *allocator, const gchar *str)
{
    return wmem_strbuf_new_len(allocator, str, str ? strlen(str) : 0);
}

wmem_strbuf_t *
wmem_strbuf_dup(wmem_allocator_t *allocator, const wmem_strbuf_t *src)
{
    wmem_strbuf_t *new;

    new = wmem_strbuf_new_sized(allocator, src->alloc_size);
    new->len = src->len;
    memcpy(new->str, src->str, new->len);
    new->str[new->len] = '\0';
    return new;
}

/* grows the allocated size of the wmem_strbuf_t. If max_size is set, then
 * not guaranteed to grow by the full amount to_add */
static inline void
wmem_strbuf_grow(wmem_strbuf_t *strbuf, const size_t to_add)
{
    size_t  new_alloc_len, new_len;

    /* short-circuit for efficiency if we have room already; greatly speeds up
     * repeated calls to wmem_strbuf_append_c and others which grow a little bit
     * at a time.
     */
    if (WMEM_STRBUF_ROOM(strbuf) >= to_add) {
        return;
    }

    new_alloc_len = strbuf->alloc_size;
    new_len = strbuf->len + to_add;

    /* +1 for the null-terminator */
    while (new_alloc_len < (new_len + 1)) {
        new_alloc_len *= 2;
    }

    if (new_alloc_len == strbuf->alloc_size) {
        return;
    }

    strbuf->str = (gchar *)wmem_realloc(strbuf->allocator, strbuf->str, new_alloc_len);

    strbuf->alloc_size = new_alloc_len;
}

void
wmem_strbuf_append(wmem_strbuf_t *strbuf, const gchar *str)
{
    size_t append_len;

    if (!str || str[0] == '\0') {
        return;
    }

    append_len = strlen(str);
    wmem_strbuf_grow(strbuf, append_len);

    ws_assert(WMEM_STRBUF_RAW_ROOM(strbuf) >= append_len + 1);
    memcpy(&strbuf->str[strbuf->len], str, append_len);
    strbuf->len += append_len;
    strbuf->str[strbuf->len] = '\0';
}

void
wmem_strbuf_append_len(wmem_strbuf_t *strbuf, const gchar *str, size_t append_len)
{

    if (!append_len || !str) {
        return;
    }

    wmem_strbuf_grow(strbuf, append_len);

    memcpy(&strbuf->str[strbuf->len], str, append_len);
    strbuf->len += append_len;
    strbuf->str[strbuf->len] = '\0';
}

static inline
int _strbuf_vsnprintf(wmem_strbuf_t *strbuf, const char *format, va_list ap)
{
    int want_len;
    char *buffer = &strbuf->str[strbuf->len];
    size_t buffer_size = WMEM_STRBUF_RAW_ROOM(strbuf);

    want_len = vsnprintf(buffer, buffer_size, format, ap);
    if (want_len < 0) {
        /* Error. */
        g_warning("%s: vsnprintf: (%d) %s", G_STRFUNC, want_len, g_strerror(errno));
        return -1;
    }
    if ((size_t)want_len < buffer_size) {
        /* Success. */
        strbuf->len += want_len;
        return 0;
    }

    /* Not enough space in buffer, output was truncated. */
    strbuf->str[strbuf->len] = '\0'; /* Reset. */

    return want_len; /* Length (not including terminating null) that would be written
                        if there was enough space in buffer. */
}

void
wmem_strbuf_append_vprintf(wmem_strbuf_t *strbuf, const gchar *fmt, va_list ap)
{
    int want_len;
    va_list ap2;

    va_copy(ap2, ap);
    /* Try to write buffer, check if output fits. */
    want_len = _strbuf_vsnprintf(strbuf, fmt, ap2);
    va_end(ap2);
    if (want_len <= 0)
        return;

    /* Resize buffer and try again. */
    wmem_strbuf_grow(strbuf, want_len);
    want_len = _strbuf_vsnprintf(strbuf, fmt, ap);
    /* Second time must succeed or error out. */
    ws_assert(want_len <= 0);
}

void
wmem_strbuf_append_printf(wmem_strbuf_t *strbuf, const gchar *format, ...)
{
    va_list ap;

    va_start(ap, format);
    wmem_strbuf_append_vprintf(strbuf, format, ap);
    va_end(ap);
}

void
wmem_strbuf_append_c(wmem_strbuf_t *strbuf, const gchar c)
{
    wmem_strbuf_grow(strbuf, 1);

    strbuf->str[strbuf->len] = c;
    strbuf->len++;
    strbuf->str[strbuf->len] = '\0';
}

void
wmem_strbuf_append_c_count(wmem_strbuf_t *strbuf, const gchar c, size_t count)
{
    wmem_strbuf_grow(strbuf, count);

    while (count-- > 0) {
        strbuf->str[strbuf->len++] = c;
    }
    strbuf->str[strbuf->len] = '\0';
}

void
wmem_strbuf_append_unichar(wmem_strbuf_t *strbuf, const gunichar c)
{
    gchar buf[6];
    size_t charlen;

    charlen = g_unichar_to_utf8(c, buf);

    wmem_strbuf_grow(strbuf, charlen);

    memcpy(&strbuf->str[strbuf->len], buf, charlen);
    strbuf->len += charlen;
    strbuf->str[strbuf->len] = '\0';
}

void
wmem_strbuf_append_unichar_validated(wmem_strbuf_t *strbuf, const gunichar c)
{
    if (g_unichar_validate(c)) {
        wmem_strbuf_append_unichar(strbuf, c);
    } else {
        wmem_strbuf_append_unichar(strbuf, UNICODE_REPLACEMENT_CHARACTER);
    }
}

static const char hex[16] = { '0', '1', '2', '3', '4', '5', '6', '7',
                              '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };

#define HEX_CODELEN 4

void
wmem_strbuf_append_hex(wmem_strbuf_t *strbuf, uint8_t ch)
{
    wmem_strbuf_grow(strbuf, HEX_CODELEN * 1);

    strbuf->str[strbuf->len++] = '\\';
    strbuf->str[strbuf->len++] = 'x';
    strbuf->str[strbuf->len++] = hex[(ch >> 4) & 0xF];
    strbuf->str[strbuf->len++] = hex[(ch >> 0) & 0xF];
    strbuf->str[strbuf->len] = '\0';
}

#define BMP_CODELEN 6

static inline
void append_hex_bmp(wmem_strbuf_t *strbuf, gunichar ch)
{
    wmem_strbuf_grow(strbuf, BMP_CODELEN * 1);

    strbuf->str[strbuf->len++] = '\\';
    strbuf->str[strbuf->len++] = 'u';
    strbuf->str[strbuf->len++] = hex[(ch >> 12) & 0xF];
    strbuf->str[strbuf->len++] = hex[(ch >>  8) & 0xF];
    strbuf->str[strbuf->len++] = hex[(ch >>  4) & 0xF];
    strbuf->str[strbuf->len++] = hex[(ch >>  0) & 0xF];
    strbuf->str[strbuf->len] = '\0';
}

#define ANY_CODELEN 10

static inline
void append_hex_any(wmem_strbuf_t *strbuf, gunichar ch)
{
    wmem_strbuf_grow(strbuf, ANY_CODELEN * 1);

    strbuf->str[strbuf->len++] = '\\';
    strbuf->str[strbuf->len++] = 'U';
    strbuf->str[strbuf->len++] = hex[(ch >> 28) & 0xF];
    strbuf->str[strbuf->len++] = hex[(ch >> 24) & 0xF];
    strbuf->str[strbuf->len++] = hex[(ch >> 20) & 0xF];
    strbuf->str[strbuf->len++] = hex[(ch >> 16) & 0xF];
    strbuf->str[strbuf->len++] = hex[(ch >> 12) & 0xF];
    strbuf->str[strbuf->len++] = hex[(ch >>  8) & 0xF];
    strbuf->str[strbuf->len++] = hex[(ch >>  4) & 0xF];
    strbuf->str[strbuf->len++] = hex[(ch >>  0) & 0xF];
    strbuf->str[strbuf->len] = '\0';
}

size_t
wmem_strbuf_append_hex_unichar(wmem_strbuf_t *strbuf, gunichar ch)
{
    if (ch <= 0x7f) {
        wmem_strbuf_append_hex(strbuf, (uint8_t)ch);
        return HEX_CODELEN;
    }
    if (ch <= 0xffff) {
        append_hex_bmp(strbuf, ch);
        return BMP_CODELEN;
    }
    append_hex_any(strbuf, ch);
    return ANY_CODELEN;
}

void
wmem_strbuf_truncate(wmem_strbuf_t *strbuf, const size_t len)
{
    if (len >= strbuf->len) {
        return;
    }

    strbuf->str[len] = '\0';
    strbuf->len = len;
}

const gchar *
wmem_strbuf_get_str(const wmem_strbuf_t *strbuf)
{
    return strbuf->str;
}

size_t
wmem_strbuf_get_len(const wmem_strbuf_t *strbuf)
{
    return strbuf->len;
}

static inline int
_memcmp_len(const void *s1, size_t s1_len, const void *s2, size_t s2_len)
{
    size_t len;
    int cmp;

    len = MIN(s1_len, s2_len);
    if ((cmp = memcmp(s1, s2, len)) != 0)
        return cmp;
    if (s1_len < s2_len)
        return -1;
    if (s1_len > s2_len)
        return 1;
    return 0;
}

WS_DLL_PUBLIC
int
wmem_strbuf_strcmp(const wmem_strbuf_t *sb1, const wmem_strbuf_t *sb2)
{
    return _memcmp_len(sb1->str, sb1->len, sb2->str, sb2->len);
}

const char *
wmem_strbuf_strstr(const wmem_strbuf_t *haystack, const wmem_strbuf_t *needle)
{
    return ws_memmem(haystack->str, haystack->len, needle->str, needle->len);
}

/* Truncates the allocated memory down to the minimal amount, frees the header
 * structure, and returns a non-const pointer to the raw string. The
 * wmem_strbuf_t structure cannot be used after this is called.
 */
char *
wmem_strbuf_finalize(wmem_strbuf_t *strbuf)
{
    if (strbuf == NULL)
        return NULL;

    char *ret = (char *)wmem_realloc(strbuf->allocator, strbuf->str, strbuf->len+1);

    wmem_free(strbuf->allocator, strbuf);

    return ret;
}

void
wmem_strbuf_destroy(wmem_strbuf_t *strbuf)
{
    if (strbuf == NULL)
        return;

    wmem_free(strbuf->allocator, strbuf->str);
    wmem_free(strbuf->allocator, strbuf);
}

static bool
string_utf8_validate(const char *str, ssize_t max_len, const char **endpptr)
{
    bool valid;
    const char *endp;

    if (max_len <= 0) {
        if (endpptr) {
            *endpptr = str;
        }
        return true;
    }

    valid = g_utf8_validate(str, max_len, &endp);

    if (valid || *endp != '\0') {
        if (endpptr) {
            *endpptr = endp;
        }
        return valid;
    }

    /* Invalid because of a nul byte. Skip nuls and continue. */
    max_len -= endp - str;
    str = endp;
    while (max_len > 0 && *str == '\0') {
        str++;
        max_len--;
    }
    return string_utf8_validate(str, max_len, endpptr);
}

/* g_utf8_validate() returns FALSE in the string contains embedded NUL
 * bytes. We accept \x00 as valid and work around that to validate the
 * entire len bytes. */
bool
wmem_strbuf_utf8_validate(wmem_strbuf_t *strbuf, const char **endpptr)
{
    return string_utf8_validate(strbuf->str, strbuf->len, endpptr);
}

void
wmem_strbuf_utf8_make_valid(wmem_strbuf_t *strbuf)
{
    wmem_strbuf_t *tmp = ws_utf8_make_valid_strbuf(strbuf->allocator, strbuf->str, strbuf->len);

    wmem_free(strbuf->allocator, strbuf->str);
    strbuf->str = tmp->str;
    strbuf->len = tmp->len;
    strbuf->alloc_size = tmp->alloc_size;

    wmem_free(strbuf->allocator, tmp);
}

/*
 * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
 *
 * Local variables:
 * c-basic-offset: 4
 * tab-width: 8
 * indent-tabs-mode: nil
 * End:
 *
 * vi: set shiftwidth=4 tabstop=8 expandtab:
 * :indentSize=4:tabSize=8:noTabs=true:
 */