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POmalloc.c:3074 + Valgrind output
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3104864
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3104912
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2
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4
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2010-06-23T19:27:36.463
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2010-06-23T20:39:49.940
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2010-06-23T20:39:49.940
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I am getting the infamous malloc.c:3074 error when running my code (compiles without issue). I compiled using the -g option. I used Valgrind to determine where the memory allocation issue is happening but the results aren't helping a whole lot. Here is the Valgrind output: <pre><code>==2710== Invalid write of size 8 ==2710== at 0x400FC8: generatePairs (ldbalpha.c:42) ==2710== by 0x400BFA: main (ldb-stegoencoderalpha.c:53) ==2710== Address 0x51997c8 is not stack'd, malloc'd or (recently) free'd ==2710== ==2710== Invalid write of size 8 ==2710== at 0x401047: generatePairs (ldbalpha.c:54) ==2710== by 0x400BFA: main (ldb-stegoencoderalpha.c:53) ==2710== Address 0x51997a8 is 0 bytes after a block of size 1,160 alloc'd ==2710== at 0x4C25153: malloc (vg_replace_malloc.c:195) ==2710== by 0x400BA6: main (ldb-stegoencoderalpha.c:49) ==2710== ==2710== Invalid write of size 8 ==2710== at 0x401054: generatePairs (ldbalpha.c:55) ==2710== by 0x400BFA: main (ldb-stegoencoderalpha.c:53) ==2710== Address 0x51997b0 is 8 bytes after a block of size 1,160 alloc'd ==2710== at 0x4C25153: malloc (vg_replace_malloc.c:195) ==2710== by 0x400BA6: main (ldb-stegoencoderalpha.c:49) ==2710== ==2710== Invalid write of size 8 ==2710== at 0x401062: generatePairs (ldbalpha.c:56) ==2710== by 0x400BFA: main (ldb-stegoencoderalpha.c:53) ==2710== Address 0x51997c0 is not stack'd, malloc'd or (recently) free'd </code></pre> Here is the main function followed by the called function generatePairs. I listed the line numbers as comments to correspond with the valgrind output: <pre><code>#include <stdio.h> #include <stdlib.h> #include <string.h> #include <malloc.h> #include "ldb.h" int main(int argc, char * argv[]) { FILE *pFile; unsigned char *buffer; int i, j; char ch = '\0'; long unsigned int lSize; if (argc != 3) { fprintf(stderr, "Usage: ./ldb-stegoencoderalpha [Stegofile] [messages.txt] > [messages-encoded.txt]\n"); return 1; } // end if pFile = fopen ( argv[1] , "r" ); if (pFile==NULL) {fputs ("File error on arg[1]",stderr); exit (1);} // obtain file size: fseek (pFile , 0 , SEEK_END); // Go to end of File lSize = ftell (pFile); // Return # of Bytes in the file rewind (pFile); // Rewind to start of file // allocate memory to contain the whole file: buffer = malloc(sizeof(char) * lSize+1); if (buffer == NULL) {fputs ("Memory error",stderr); exit (2);} bitpair * ppairs = malloc(sizeof(bitpair) * (lSize+1)); // Line 49,Structure setup memset (ppairs, 0, sizeof(bitpair) * (lSize+1)); //zeroize it first generatePairs(ppairs, lSize+1); //Line 53 in Valgrind error </code></pre> After that I do some calculations with those pairs but the Valgrind errors are coming from the generatePairs and malloc functions. Here is the generatePairs function: <pre><code>#include <string.h> #include <assert.h> #include "ldb.h" void generatePairs(bitpair * ppairs, long unsigned int bits) { unsigned int i, rand1, rand2, high, low; unsigned int count = 1; // initialize the array of pairs for(i = 1; i <= bits; i++) { bitpair * bp = &ppairs[i]; bp->ref = -1; bp->enc = -1; bp->len = -1; bp->bit = -1; bp->used = 0; } for(i = 1; i <= bits; i++) { rand1 = 0; ppairs[rand1].used = 1; rand2 = count; count++; assert(rand2 <= bits); ppairs[rand2].used = 1; //Line 42 in Valgrind error high = rand2; low = rand1; // initialize both data structures (bp->used is already set) bitpair * bp = &ppairs[low]; bp->ref = low; bp->enc = high; bp->bit = i; bp = &ppairs[high]; bp->ref = low; //Line 54 in Valgrind error bp->enc = high; //Line 55 in Valgrind error bp->bit = i; //Line 56 in Valgrind error } return; } typedef struct { long unsigned int ref; long unsigned int enc; long unsigned int len; long unsigned int bit; long unsigned int used; } bitpair; void generatePairs(bitpair * ppairs, long unsigned int bits); </code></pre> Thanks!
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<c><malloc><valgrind>
Title
malloc.c:3074 + Valgrind output
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