Eu estou tentando alocar dinamicamente um array 2D para armazenar um arquivo bmp com o seguinte código:
#include <stdio.h> #include <stdlib.h> int height, width; // variables for the image height and width int** storeImage (FILE* fil) { // function that reads and stores the image in a matrix int** img; char* trash = malloc(255 * sizeof(char)); fscanf (fil, "%s", trash); free(trash); fscanf (fil, "%d", &width); fscanf (fil, "%d", &height); img = malloc (height * sizeof(int*)); for (int i = 0; i < height; i++) { img[i] = malloc (width * sizeof(int)); } fscanf (fil, "%d", &img[0][0]); for (int i = 0; i < height; i++) { // for that fills the matrix img for (int j = 0; j < width; j++) { fscanf (fil, "%d", &img[i][j]); } } return img; } int main (void) { char* file_name = malloc(255 * sizeof(char)); scanf("%[^\n]s", file_name); getc(stdin); // consumes the '\n' or '\r' FILE* fil = NULL; fil = fopen(file_name, "r"); int** img = storeImage(fil); // pointer to the matrix that represents the image fclose(fil); for (int i = 0; i < height; i++) { // for that prints the matrix img for (int j = 0; j < width; j++) { printf("%d ", img[i][j]); } printf("\n"); } for (int i = 0; i < height; i++) { free(img[i]); } free (img); free (file_name); return 0; } O arquivo que estou lendo tem o seguinte formato:
P2 5 6 255 10 13 18 12 11 11 10 17 10 19 16 17 19 11 12 18 18 17 16 17 13 12 19 13 15 16 10 11 19 14 A princípio, o programa funciona e printa o que eu quero no terminal. Porém, quando eu rodo ele no Valgrind, eu recebo um Segmentation fault (core dumped):
==8965== Syscall param openat(filename) points to uninitialised byte(s) ==8965== at 0x4B0E0EE: open (in /usr/lib/libc-2.26.so) ==8965== by 0x4AA0CE2: _IO_file_open (in /usr/lib/libc-2.26.so) ==8965== by 0x4AA0EB1: _IO_file_fopen@@GLIBC_2.2.5 (in /usr/lib/libc-2.26.so) ==8965== by 0x4A94715: __fopen_internal (in /usr/lib/libc-2.26.so) ==8965== by 0x108AC5: main (in /home/aluno/Projetos/debug) ==8965== Address 0x4dde040 is 0 bytes inside a block of size 255 alloc'd ==8965== at 0x403077F: malloc (vg_replace_malloc.c:299) ==8965== by 0x108A7F: main (in /home/aluno/Projetos/debug) ==8965== ==8965== Invalid read of size 4 ==8965== at 0x4A91F4D: __isoc99_fscanf (in /usr/lib/libc-2.26.so) ==8965== by 0x108930: storeImage (in /home/aluno/Projetos/debug) ==8965== by 0x108AD5: main (in /home/aluno/Projetos/debug) ==8965== Address 0x0 is not stack'd, malloc'd or (recently) free'd ==8965== ==8965== ==8965== Process terminating with default action of signal 11 (SIGSEGV): dumping core ==8965== Access not within mapped region at address 0x0 ==8965== at 0x4A91F4D: __isoc99_fscanf (in /usr/lib/libc-2.26.so) ==8965== by 0x108930: storeImage (in /home/aluno/Projetos/debug) ==8965== by 0x108AD5: main (in /home/aluno/Projetos/debug) ==8965== If you believe this happened as a result of a stack ==8965== overflow in your program's main thread (unlikely but ==8965== possible), you can try to increase the size of the ==8965== main thread stack using the --main-stacksize= flag. ==8965== The main thread stack size used in this run was 8388608. ==8965== ==8965== HEAP SUMMARY: ==8965== in use at exit: 510 bytes in 2 blocks ==8965== total heap usage: 4 allocs, 2 frees, 2,086 bytes allocated ==8965== ==8965== LEAK SUMMARY: ==8965== definitely lost: 0 bytes in 0 blocks ==8965== indirectly lost: 0 bytes in 0 blocks ==8965== possibly lost: 0 bytes in 0 blocks ==8965== still reachable: 510 bytes in 2 blocks ==8965== suppressed: 0 bytes in 0 blocks ==8965== Reachable blocks (those to which a pointer was found) are not shown. ==8965== To see them, rerun with: --leak-check=full --show-leak-kinds=all ==8965== ==8965== For counts of detected and suppressed errors, rerun with: -v ==8965== Use --track-origins=yes to see where uninitialised values come from ==8965== ERROR SUMMARY: 2 errors from 2 contexts (suppressed: 0 from 0) Segmentation fault (core dumped) Qual o motivo desse erro?
The post Como alocar memória dinamicamente para um array 2D que armazena os pixels de um arquivo bmp em C? appeared first on 100% Private Proxies - Fast, Anonymous, Quality, Unlimited USA Private Proxy!.
