strbuf.c

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#include "cache.h"
#include <linux/kernel.h>

int prefixcmp(const char *str, const char *prefix)
{
    for (; ; str++, prefix++)
        if (!*prefix)
            return 0;
        else if (*str != *prefix)
            return (unsigned char)*prefix - (unsigned char)*str;
}

/*
 * Used as the default ->buf value, so that people can always assume
 * buf is non NULL and ->buf is NUL terminated even for a freshly
 * initialized strbuf.
 */
char strbuf_slopbuf[1];

void strbuf_init(struct strbuf *sb, ssize_t hint)
{
    sb->alloc = sb->len = 0;
    sb->buf = strbuf_slopbuf;
    if (hint)
        strbuf_grow(sb, hint);
}

void strbuf_release(struct strbuf *sb)
{
    if (sb->alloc) {
        free(sb->buf);
        strbuf_init(sb, 0);
    }
}

char *strbuf_detach(struct strbuf *sb, size_t *sz)
{
    char *res = sb->alloc ? sb->buf : NULL;
    if (sz)
        *sz = sb->len;
    strbuf_init(sb, 0);
    return res;
}

void strbuf_grow(struct strbuf *sb, size_t extra)
{
    if (sb->len + extra + 1 <= sb->len)
        die("you want to use way too much memory");
    if (!sb->alloc)
        sb->buf = NULL;
    ALLOC_GROW(sb->buf, sb->len + extra + 1, sb->alloc);
}

static void strbuf_splice(struct strbuf *sb, size_t pos, size_t len,
                   const void *data, size_t dlen)
{
    if (pos + len < pos)
        die("you want to use way too much memory");
    if (pos > sb->len)
        die("`pos' is too far after the end of the buffer");
    if (pos + len > sb->len)
        die("`pos + len' is too far after the end of the buffer");

    if (dlen >= len)
        strbuf_grow(sb, dlen - len);
    memmove(sb->buf + pos + dlen,
            sb->buf + pos + len,
            sb->len - pos - len);
    memcpy(sb->buf + pos, data, dlen);
    strbuf_setlen(sb, sb->len + dlen - len);
}

void strbuf_remove(struct strbuf *sb, size_t pos, size_t len)
{
    strbuf_splice(sb, pos, len, NULL, 0);
}

void strbuf_add(struct strbuf *sb, const void *data, size_t len)
{
    strbuf_grow(sb, len);
    memcpy(sb->buf + sb->len, data, len);
    strbuf_setlen(sb, sb->len + len);
}

void strbuf_addf(struct strbuf *sb, const char *fmt, ...)
{
    int len;
    va_list ap;

    if (!strbuf_avail(sb))
        strbuf_grow(sb, 64);
    va_start(ap, fmt);
    len = vsnprintf(sb->buf + sb->len, sb->alloc - sb->len, fmt, ap);
    va_end(ap);
    if (len < 0)
        die("your vsnprintf is broken");
    if (len > strbuf_avail(sb)) {
        strbuf_grow(sb, len);
        va_start(ap, fmt);
        len = vsnprintf(sb->buf + sb->len, sb->alloc - sb->len, fmt, ap);
        va_end(ap);
        if (len > strbuf_avail(sb)) {
            die("this should not happen, your vsnprintf is broken");
        }
    }
    strbuf_setlen(sb, sb->len + len);
}

ssize_t strbuf_read(struct strbuf *sb, int fd, ssize_t hint)
{
    size_t oldlen = sb->len;
    size_t oldalloc = sb->alloc;

    strbuf_grow(sb, hint ? hint : 8192);
    for (;;) {
        ssize_t cnt;

        cnt = read(fd, sb->buf + sb->len, sb->alloc - sb->len - 1);
        if (cnt < 0) {
            if (oldalloc == 0)
                strbuf_release(sb);
            else
                strbuf_setlen(sb, oldlen);
            return -1;
        }
        if (!cnt)
            break;
        sb->len += cnt;
        strbuf_grow(sb, 8192);
    }

    sb->buf[sb->len] = '\0';
    return sb->len - oldlen;
}