lz4.c

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#include "config.h"
#include <limits.h>
#include <lz4.h>
#include <stddef.h>
#include "private.h"
#include "mutt/lib.h"
#include "lib.h"
 
#define MIN_COMP_LEVEL 1  
#define MAX_COMP_LEVEL 12 
 
struct Lz4ComprData
{
  void *buf;   
  short level; 
};
 
void lz4_cdata_free(struct Lz4ComprData **ptr)
{
  if (!ptr || !*ptr)
    return;
 
  struct Lz4ComprData *cdata = *ptr;
  FREE(&cdata->buf);
 
  FREE(ptr);
}
 
static struct Lz4ComprData *lz4_cdata_new(void)
{
  return MUTT_MEM_CALLOC(1, struct Lz4ComprData);
}
 
static ComprHandle *compr_lz4_open(short level)
{
  struct Lz4ComprData *cdata = lz4_cdata_new();
 
  cdata->buf = mutt_mem_calloc(LZ4_compressBound(1024 * 32), 1);
 
  if ((level < MIN_COMP_LEVEL) || (level > MAX_COMP_LEVEL))
  {
    mutt_debug(LL_DEBUG1, "The compression level for %s should be between %d and %d",
               compr_lz4_ops.name, MIN_COMP_LEVEL, MAX_COMP_LEVEL);
    level = MIN_COMP_LEVEL;
  }
 
  cdata->level = level;
 
  // Return an opaque pointer
  return (ComprHandle *) cdata;
}
 
static void *compr_lz4_compress(ComprHandle *handle, const char *data,
                                size_t dlen, size_t *clen)
{
  if (!handle || (dlen > INT_MAX))
    return NULL;
 
  // Decloak an opaque pointer
  struct Lz4ComprData *cdata = handle;
 
  int datalen = dlen;
  int len = LZ4_compressBound(dlen);
  if (len > (INT_MAX - 4))
    return NULL; // LCOV_EXCL_LINE
  mutt_mem_realloc(&cdata->buf, len + 4);
  char *cbuf = cdata->buf;
 
  len = LZ4_compress_fast(data, cbuf + 4, datalen, len, cdata->level);
  if (len == 0)
    return NULL; // LCOV_EXCL_LINE
  *clen = len + 4;
 
  /* save ulen to first 4 bytes */
  unsigned char *cs = cdata->buf;
  cs[0] = dlen & 0xff;
  dlen >>= 8;
  cs[1] = dlen & 0xff;
  dlen >>= 8;
  cs[2] = dlen & 0xff;
  dlen >>= 8;
  cs[3] = dlen & 0xff;
 
  return cdata->buf;
}
 
static void *compr_lz4_decompress(ComprHandle *handle, const char *cbuf, size_t clen)
{
  if (!handle)
    return NULL;
 
  // Decloak an opaque pointer
  struct Lz4ComprData *cdata = handle;
 
  /* first 4 bytes store the size */
  const unsigned char *cs = (const unsigned char *) cbuf;
  if (clen < 4)
    return NULL;
  size_t ulen = cs[0] + (cs[1] << 8) + (cs[2] << 16) + ((size_t) cs[3] << 24);
  if (ulen > INT_MAX)
    return NULL; // LCOV_EXCL_LINE
  if (ulen == 0)
    return (void *) cbuf;
 
  mutt_mem_realloc(&cdata->buf, ulen);
  void *ubuf = cdata->buf;
  const char *data = cbuf;
  int rc = LZ4_decompress_safe(data + 4, ubuf, clen - 4, ulen);
  if (rc < 0)
    return NULL;
 
  return ubuf;
}
 
static void compr_lz4_close(ComprHandle **ptr)
{
  if (!ptr || !*ptr)
    return;
 
  // Decloak an opaque pointer
  lz4_cdata_free((struct Lz4ComprData **) ptr);
}
 
COMPRESS_OPS(lz4, MIN_COMP_LEVEL, MAX_COMP_LEVEL)