buffer.c

/****************************************************************************/
/*          pfixtools: a collection of postfix related tools                */
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/****************************************************************************/

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

#include "mem.h"
#include "buffer.h"

int buffer_addvf(buffer_t *buf, const char *fmt, va_list ap)
{
    int len, avail = buf->size - buf->len;
    va_list ap2;

    va_copy(ap2, ap);

    len = vsnprintf(buf->data + buf->len, (size_t)avail, fmt, ap);
    if (len >= avail) {
        buffer_resize(buf, buf->len + len);
        avail = buf->size - buf->len;
        len = vsnprintf(buf->data + buf->len, (size_t)avail, fmt, ap2);
    }
    buf->len += len;
    buf->data[buf->len] = '\0';
    va_end(ap2);
    return len;
}

void buffer_consume(buffer_t *buf, int len)
{
    if (len <= 0)
        return;

    if (len >= (int)buf->len) {
        buffer_reset(buf);
        return;
    }

    memmove(buf->data, buf->data + len, buf->len + 1 - len);
    buf->len -= len;
}

int buffer_read(buffer_t *buf, int fd, int count)
{
    int res;

    if (count < 0)
        count = BUFSIZ;

    buffer_ensure(buf, count);

    res = read(fd, buf->data + buf->len, (size_t)count);
    if (res < 0) {
        buf->data[buf->len] = '\0';
        return res;
    }

    buffer_extend(buf, res);
    return res;
}

int buffer_write(buffer_t *buf, int fd)
{
    int res = write(fd, buf->data, buf->len);
    if (res < 0) {
        return errno == EINTR || errno == EAGAIN ? 0 : -1;
    }
    buffer_consume(buf, res);
    return res;
}

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