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POMalloc errors when using POSIX threads on OSX
 

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  1. POMalloc errors when using POSIX threads on OSX
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    <p>I am currently completing final year assignments for my BSc in Computer Science one of which is on concurrency using POSIX threads. The assignment is a very simple http server that handles http requests in separate threads and returns simple html files. I have been experiencing some signal abort errors when freeing and nullifying the char buffers at the end of the thread functions. I am working in X-Code and when I enable Guard Malloc in the scheme it works just fine. Also if I remove the calls to free() and the nullification the program runs fine too. The latter I am assuming is consuming the memory used in the previous threads and not freeing it up for other processes and therefore is not a good solution, correct? I do not understand Guard Malloc but as I will hand in a raw .cpp file for compilation on the Lecturer's Linux machine the support will not be compiled.</p> <p>Below is the complete code. Any comments, style critique or pearls of wisdom of any kind you are willing to throw my way are deeply appreciated.</p> <p>The input that is crashing this is the .html homepage from this random website - <a href="http://www.budgie-info.com/" rel="nofollow">http://www.budgie-info.com/</a></p> <p>Many thanks in advance. </p> <pre><code>#include &lt;string.h&gt; #include &lt;stdio.h&gt; #include &lt;stdlib.h&gt; #include &lt;string.h&gt; #include &lt;unistd.h&gt; #include &lt;errno.h&gt; #include &lt;sys/types.h&gt; #include &lt;sys/socket.h&gt; #include &lt;netinet/in.h&gt; #include &lt;pthread.h&gt; // Define the port number to identify this process #define MYPORT 3490 typedef struct socket_fd { unsigned fd; } sock_fd; void *request(void *fd); int main() { int s; //unsigned fd; struct sockaddr_in my_addr; pthread_t t; int retval; sock_fd *s_fd; // Construct address information my_addr.sin_family = AF_INET; my_addr.sin_port = htons(MYPORT); my_addr.sin_addr.s_addr = INADDR_ANY; memset(my_addr.sin_zero, '\0', sizeof(my_addr.sin_zero) ); // Create a socket and bind it the port MYPORT s=socket(PF_INET,SOCK_STREAM, 0); int yes = 1; setsockopt(s, SOL_SOCKET, SO_REUSEADDR, &amp;yes, sizeof(int)); retval = bind(s, (struct sockaddr *)&amp;my_addr, sizeof(my_addr)); if( retval != 0) { fputs ("bind() failed.",stderr); exit (7); } printf("%d\n", my_addr.sin_port); retval = listen(s,10); if( retval != 0 ) { // Allow up to 10 incoming connections fputs ("listen() failed.",stderr); exit (9); } while(1) { s_fd = (sock_fd*)malloc(sizeof(sock_fd)); s_fd-&gt;fd=accept(s,NULL,NULL); // wait for a request retval = pthread_create( &amp;t, NULL, request, s_fd); free(s_fd); s_fd = NULL; if(retval != 0) { printf("pthread_create() failed. error %d\n", retval); } } } void *request(void *s_fd) { int retval; char data[65536]; char header[]="HTTP/1.1 200 OK\r\nContent-Type: text/html\r\n\r\n"; char header_gif[]="HTTP/1.1 200 OK\r\nContent-Type: image/gif\r\n\r\n"; char header_jpeg[]="HTTP/1.1 200 OK\r\nContent-Type: image/jpeg\r\n\r\n"; char header_png[]="HTTP/1.1 200 OK\r\nContent-Type: image/png\r\n\r\n"; int header_len; char *send_buffer; char *temp_buffer; char filename[256]; char filename_parsed[256]; FILE *f; sock_fd *fd_t = (sock_fd*)s_fd; unsigned fd = fd_t-&gt;fd; int cnt = 0; do { retval=(int)recv(fd,data,65536,0); // recieve the request using fd ++cnt; } while(retval == 65536); if(retval &lt; 0) { fputs ("recv() failed.\n",stderr); return NULL; } data[retval]='\0'; // NUL terminate it retval = sscanf((char *)data,"GET /%s ",filename); // get the name of the file if(retval != 1) { fputs ("sscanf() failed.\n",stderr); return NULL; } if(strlen(filename) &gt; 256) { fputs ("Filename overflow.\n",stderr); return NULL; } // parse uml spaces out of filenames int j = 0; for(int i = 0; filename[i]!='\0'; ++i) { if(filename[i] == '%') { filename_parsed[j] = ' '; i+=2; } else { filename_parsed[j] = filename[i]; } ++j; } filename_parsed[j] = '\0'; //print received header printf("Receiving:\n %s\n", data); //print requested filename printf("\n\n-------------filename = %s|\n\n", filename_parsed); if( (f=fopen(filename_parsed,"rb")) == NULL ) { // open the file (might be binary) fputs ("fopen() failed.\n",stderr); return NULL; } // obtain file size: size_t lSize; fseek (f , 0 , SEEK_END); lSize = ftell (f); rewind (f); // pre calculate length of filename int len = (int)strlen(filename_parsed); // identify appropriate header, alocate required memory and copy the header into the buffer if(0 == strcmp(filename_parsed + len - 4, ".gif")) { header_len = (int)strlen(header_gif); printf("\n\n\n\n\nG I F\n\n\n\n"); send_buffer = (char*) malloc ( sizeof(char)*((lSize+(size_t)header_len)+14) ); // WARNING: hardcoded margin for header size differences memcpy(send_buffer, header_gif, header_len); } else if(0 == strcmp(filename_parsed + len - 5, ".jpeg")) { printf("\n\n\n\n\nJ P E G\n\n\n\n"); header_len = (int)strlen(header_jpeg); send_buffer = (char*) malloc ( sizeof(char)*((lSize+(size_t)header_len)+14) ); // WARNING: hardcoded margin for header size differences memcpy(send_buffer, header_jpeg, header_len); } else if(0 == strcmp(filename_parsed + len - 4, ".png")) { header_len = (int)strlen(header_png); printf("\n\n\n\n\nP N G \n\n\n\n"); send_buffer = (char*) malloc ( sizeof(char)*((lSize+(size_t)header_len)+14) ); // WARNING: hardcoded margin for header size differences memcpy(send_buffer, header_png, header_len); } else { header_len = (int)strlen(header); send_buffer = (char*) malloc ( sizeof(char)*((lSize+(size_t)header_len)+14) ); // WARNING: hardcoded margin for header size differences memcpy(send_buffer, header, header_len); } // allocate memory to contain the whole file: temp_buffer = (char*) malloc (sizeof(char)*(lSize+10)); // WARNING: hardcoded margin for header size differences if (temp_buffer == NULL) { fputs ("malloc() failed.\n",stderr); return NULL; } // copy the file into the buffer: retval = (int)fread (temp_buffer,1,lSize,f); if (retval != lSize) { fputs ("fread() failed.\n",stderr); return NULL; } memcpy(send_buffer + header_len, temp_buffer, retval); //print packet being sent printf("Sending:\n%s\n", send_buffer); memcpy(send_buffer + retval, "\r\n", 4); // send packet retval = (int)send(fd,send_buffer,retval,0); if(retval &lt; 0) { fputs ("send() failed.\n",stderr); return NULL; } free(temp_buffer); // The section of memory management causes SIGABRT errors everytime i run, commenting them out made it run smoothly. temp_buffer = NULL; // Is the closing of this function tidying up for me or is it leaving a memory leak trail? free(send_buffer); // Is it the multi threading that is making memory management buggy? send_buffer = NULL; fclose(f); f = NULL; close(fd); // close the socket return NULL; } </code></pre>
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