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Diffstat (limited to 'src/dstring.c')
| -rw-r--r-- | src/dstring.c | 220 |
1 files changed, 220 insertions, 0 deletions
diff --git a/src/dstring.c b/src/dstring.c new file mode 100644 index 0000000..f344d09 --- /dev/null +++ b/src/dstring.c @@ -0,0 +1,220 @@ +/**************************************************************************** + * bfs * + * Copyright (C) 2016-2022 Tavian Barnes <tavianator@tavianator.com> * + * * + * Permission to use, copy, modify, and/or distribute this software for any * + * purpose with or without fee is hereby granted. * + * * + * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES * + * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF * + * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR * + * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES * + * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN * + * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF * + * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. * + ****************************************************************************/ + +#include "dstring.h" +#include <assert.h> +#include <stdarg.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> + +/** + * The memory representation of a dynamic string. Users get a pointer to data. + */ +struct dstring { + size_t capacity; + size_t length; + char data[]; +}; + +/** Get the string header from the string data pointer. */ +static struct dstring *dstrheader(const char *dstr) { + return (struct dstring *)(dstr - offsetof(struct dstring, data)); +} + +/** Get the correct size for a dstring with the given capacity. */ +static size_t dstrsize(size_t capacity) { + return BFS_FLEX_SIZEOF(struct dstring, data, capacity + 1); +} + +/** Allocate a dstring with the given contents. */ +static char *dstralloc_impl(size_t capacity, size_t length, const char *data) { + // Avoid reallocations for small strings + if (capacity < 7) { + capacity = 7; + } + + struct dstring *header = malloc(dstrsize(capacity)); + if (!header) { + return NULL; + } + + header->capacity = capacity; + header->length = length; + + memcpy(header->data, data, length); + header->data[length] = '\0'; + return header->data; +} + +char *dstralloc(size_t capacity) { + return dstralloc_impl(capacity, 0, ""); +} + +char *dstrdup(const char *str) { + size_t len = strlen(str); + return dstralloc_impl(len, len, str); +} + +char *dstrndup(const char *str, size_t n) { + size_t len = strnlen(str, n); + return dstralloc_impl(len, len, str); +} + +size_t dstrlen(const char *dstr) { + return dstrheader(dstr)->length; +} + +int dstreserve(char **dstr, size_t capacity) { + struct dstring *header = dstrheader(*dstr); + + if (capacity > header->capacity) { + capacity *= 2; + + header = realloc(header, dstrsize(capacity)); + if (!header) { + return -1; + } + header->capacity = capacity; + + *dstr = header->data; + } + + return 0; +} + +int dstresize(char **dstr, size_t length) { + if (dstreserve(dstr, length) != 0) { + return -1; + } + + struct dstring *header = dstrheader(*dstr); + header->length = length; + header->data[length] = '\0'; + + return 0; +} + +/** Common implementation of dstr{cat,ncat,app}. */ +static int dstrcat_impl(char **dest, const char *src, size_t srclen) { + size_t oldlen = dstrlen(*dest); + size_t newlen = oldlen + srclen; + + if (dstresize(dest, newlen) != 0) { + return -1; + } + + memcpy(*dest + oldlen, src, srclen); + return 0; +} + +int dstrcat(char **dest, const char *src) { + return dstrcat_impl(dest, src, strlen(src)); +} + +int dstrncat(char **dest, const char *src, size_t n) { + return dstrcat_impl(dest, src, strnlen(src, n)); +} + +int dstrdcat(char **dest, const char *src) { + return dstrcat_impl(dest, src, dstrlen(src)); +} + +int dstrapp(char **str, char c) { + return dstrcat_impl(str, &c, 1); +} + +char *dstrprintf(const char *format, ...) { + va_list args; + + va_start(args, format); + char *str = dstrvprintf(format, args); + va_end(args); + + return str; +} + +char *dstrvprintf(const char *format, va_list args) { + // Guess a capacity to try to avoid reallocating + char *str = dstralloc(2*strlen(format)); + if (!str) { + return NULL; + } + + if (dstrvcatf(&str, format, args) != 0) { + dstrfree(str); + return NULL; + } + + return str; +} + +int dstrcatf(char **str, const char *format, ...) { + va_list args; + + va_start(args, format); + int ret = dstrvcatf(str, format, args); + va_end(args); + + return ret; +} + +int dstrvcatf(char **str, const char *format, va_list args) { + // Guess a capacity to try to avoid calling vsnprintf() twice + size_t len = dstrlen(*str); + dstreserve(str, len + 2*strlen(format)); + size_t cap = dstrheader(*str)->capacity; + + va_list copy; + va_copy(copy, args); + + char *tail = *str + len; + int ret = vsnprintf(tail, cap - len + 1, format, args); + if (ret < 0) { + goto fail; + } + + size_t tail_len = ret; + if (tail_len > cap - len) { + cap = len + tail_len; + if (dstreserve(str, cap) != 0) { + goto fail; + } + + tail = *str + len; + ret = vsnprintf(tail, tail_len + 1, format, copy); + if (ret < 0 || (size_t)ret != tail_len) { + assert(!"Length of formatted string changed"); + goto fail; + } + } + + va_end(copy); + + struct dstring *header = dstrheader(*str); + header->length += tail_len; + return 0; + +fail: + *tail = '\0'; + return -1; +} + +void dstrfree(char *dstr) { + if (dstr) { + free(dstrheader(dstr)); + } +} |