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90 lines
2.3 KiB
C
90 lines
2.3 KiB
C
#include "parse.h"
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static const size_t max_ssize_t = (((size_t)1) << (sizeof(size_t)*8-1))-1;
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/* Read n bytes from stream. Return n.
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* Set stream to error state if not enough space or I/O error. */
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ssize_t prs_readblob(struct bytestream* bs,unsigned char* dest,size_t destlen) {
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ssize_t r;
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if (destlen > max_ssize_t)
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destlen = max_ssize_t;
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if (!bs_capacityassert(bs,destlen)) return -1;
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r = destlen;
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switch (bs->type) {
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case MEMBUF:
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memcpy(dest, bs->u.base+bs->cur, destlen);
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bs->cur += destlen;
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break;
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case IOBUF:
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r=buffer_get(bs->u.b, (char*)dest, destlen);
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if (r != (ssize_t)destlen) {
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bs->cur = 1; // set bytestream to error state
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bs->max = 0;
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return -1;
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}
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bs->cur += r;
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break;
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case BSTREAM:
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r=prs_readblob(bs->u.bs, dest, destlen);
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if (r != (ssize_t)destlen) {
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bs->cur = 1; // set bytestream to error state
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bs->max = 0;
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return -1;
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}
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bs->cur += r;
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break;
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}
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return r;
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}
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#ifdef UNITTEST
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#include <assert.h>
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#undef UNITTEST
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#include "buffer/bs_get.c"
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#include "buffer/bs_err.c"
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#include "buffer/bs_capacityassert.c"
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#include "buffer/bs_init_iobuf_size.c"
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#include "buffer/bs_init_membuf.c"
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#include "buffer/buffer_get.c"
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#include "buffer/buffer_getc.c"
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#include "buffer/buffer_feed.c"
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#include "buffer/buffer_stubborn2.c"
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#include "byte/byte_copy.c"
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#include "open/open_read.c"
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int main() {
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struct bytestream bs = BS_FROM_MEMBUF("\x34\x12", 2);
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unsigned char buf[42];
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assert(prs_readblob(&bs, buf, 2) == 2);
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assert(bs_err(&bs) == 0);
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assert(!memcmp(buf,"\x34\x12",2));
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assert(prs_readblob(&bs, buf, 1) == -1);
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assert(bs_err(&bs));
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// now try to provoke integer overflow
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bs_init_membuf(&bs, (const unsigned char*)"\x34\x12", 2);
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assert(bs_get(&bs) == 0x34);
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assert(prs_readblob(&bs, buf, (size_t)-1) == -1);
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// a bad implementation would add 0xffffffff to the 1 we already read and wrap to 0
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// our code makes sure not to wrap and also limits the length of the
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// blob to max_ssize_t (0x7fffffff).
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assert(bs_err(&bs));
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int fd = open_read("Makefile");
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assert(fd!=-1);
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buffer b = BUFFER_INIT(read, fd, buf+32, 10);
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bs_init_iobuf_size(&bs, &b, 100);
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assert(prs_readblob(&bs, buf, 20) == 20); // make sure we can read a 20 byte blob at once even if the iobuf buffer size is smaller
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// strace will show two read calls here
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}
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#endif
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