这是我的程序：
int main(int argc, char *argv[]){
if(argc != 2){
printf("Uso: ./server <numero porta>n");
exit(1);
}
int sockd, newsockd, LunghezzaClient;
int NumPorta = atoi(argv[1]);
struct sockaddr_in serv_addr, cli_addr; /* indirizzo del server e del client */
int rc, fd;
off_t offset = 0;
struct stat stat_buf;
char filename[1024] = {};
size_t fsize;
if((sockd = socket(AF_INET, SOCK_STREAM, 0)) < 0){
perror("Errore creazione socketn");
exit(EXIT_FAILURE);
}
bzero((char *) &serv_addr, sizeof(serv_addr)); /* bzero scrive dei null bytes dove specificato per la lunghezza specificata */
serv_addr.sin_family = AF_INET; /* la famiglia dei protocolli */
serv_addr.sin_port = htons(NumPorta); /* porta htons converte nell'ordine dei byte di rete */
serv_addr.sin_addr.s_addr = INADDR_ANY; /* dato che è un server bisogna associargli l'indirizzo della macchina su cui sta girando */
if(bind(sockd, (struct sockaddr *) &serv_addr, sizeof(serv_addr)) < 0){
perror("Errore di bindn");
onexit(NULL, sockd, NULL, 1);
}
if(listen(sockd, 5) < 0){
perror("Errore nella funzione listen");
onexit(NULL, sockd, NULL, 1);
}
LunghezzaClient = sizeof(cli_addr);
signal (SIGINT, ( void *)sig_handler);
while(1){
if((newsockd = accept(sockd, (struct sockaddr *) &cli_addr, (socklen_t *) &LunghezzaClient)) < 0){
perror("Errore nella connessionen");
onexit(newsockd, sockd, NULL, 2);
}
/* get the file name from the client */
if((rc = recv(newsockd, filename, sizeof(filename), 0)) < 0){
perror("Errore nella ricezione del nome del file");
onexit(newsockd, sockd, NULL, 2);
}
/* Terminiamo il nome del file con NULL e se ultimo carattere è n o r lo cambiamo con */
filename[rc] = ' ';
if (filename[strlen(filename)-1] == 'n')
filename[strlen(filename)-1] = ' ';
if (filename[strlen(filename)-1] == 'r')
filename[strlen(filename)-1] = ' ';
/* inet_ntoa converte un hostname in un ip decimale puntato */
fprintf(stderr, "Ricevuta richiesta di inviare il file '%s' dall' indirizzo %sn", filename, inet_ntoa(cli_addr.sin_addr));
/* open the file to be sent */
fd = open(filename, O_RDONLY);
if (fd < 0) {
fprintf(stderr, "Impossibile aprire '%s': %sn", filename, strerror(errno));
onexit(newsockd, sockd, NULL, 2);
}
/* get the size of the file to be sent */
if(fstat(fd, &stat_buf) < 0){
perror("Errore fstat");
onexit(newsockd, sockd, fd, 3);
}
fsize = stat_buf.st_size;
if(send(newsockd, &fsize, sizeof(fsize), 0) < 0){
perror("Errore durante l'invio della grandezza del filen");
onexit(newsockd, sockd, fd, 3);
}
/* copy file using sendfile */
offset = 0;
rc = sendfile(newsockd, fd, &offset, stat_buf.st_size);
if (rc == -1) {
fprintf(stderr, "Errore durante l'invio di: '%s'n", strerror(errno));
onexit(newsockd, sockd, fd, 3);
}
if (rc != fsize) {
fprintf(stderr, "Trasferimento incompleto: %d di %d bytesn", rc, (int)stat_buf.st_size);
onexit(newsockd, sockd, fd, 3);
}
onexit(newsockd, NULL, fd, 4);
}
close(sockd);
exit(EXIT_SUCCESS);
}
但是当我尝试用gcc -Wall -O3 -o program myprogram.c编译它时，由于函数中的一些错误onexit我收到了很多警告。这是我收到的警告：
server-iterativo.c: In function ‘main’:
server-iterativo.c:51:3: warning: passing argument 1 of ‘onexit’ makes integer from pointer without a cast [enabled by default]
server-iterativo.c:23:6: note: expected ‘int’ but argument is of type ‘void *’
server-iterativo.c:56:7: warning: passing argument 1 of ‘onexit’ makes integer from pointer without a cast [enabled by default]
server-iterativo.c:23:6: note: expected ‘int’ but argument is of type ‘void *’
server-iterativo.c:92:7: warning: passing argument 3 of ‘onexit’ makes pointer from integer without a cast [enabled by default]
server-iterativo.c:23:6: note: expected ‘struct FILE *’ but argument is of type ‘int’
server-iterativo.c:97:7: warning: passing argument 3 of ‘onexit’ makes pointer from integer without a cast [enabled by default]
server-iterativo.c:23:6: note: expected ‘struct FILE *’ but argument is of type ‘int’
server-iterativo.c:104:9: warning: passing argument 3 of ‘onexit’ makes pointer from integer without a cast [enabled by default]
server-iterativo.c:23:6: note: expected ‘struct FILE *’ but argument is of type ‘int’
server-iterativo.c:108:9: warning: passing argument 3 of ‘onexit’ makes pointer from integer without a cast [enabled by default]
server-iterativo.c:23:6: note: expected ‘struct FILE *’ but argument is of type ‘int’
server-iterativo.c:111:3: warning: passing argument 2 of ‘onexit’ makes integer from pointer without a cast [enabled by default]
server-iterativo.c:23:6: note: expected ‘int’ but argument is of type ‘void *’
server-iterativo.c:111:3: warning: passing argument 3 of ‘onexit’ makes pointer from integer without a cast [enabled by default]
server-iterativo.c:23:6: note: expected ‘struct FILE *’ but argument is of type ‘int’
server-iterativo.c: In function ‘onexit’:
server-iterativo.c:131:3: warning: passing argument 1 of ‘close’ makes integer from pointer without a cast [enabled by default]
/usr/include/unistd.h:354:12: note: expected ‘int’ but argument is of type ‘struct FILE *’
server-iterativo.c:136:3: warning: passing argument 1 of ‘close’ makes integer from pointer without a cast [enabled by default]
/usr/include/unistd.h:354:12: note: expected ‘int’ but argument is of type ‘struct FILE *’
我不明白为什么我得到这个错误:(
警告消息看起来很清楚：
在删除的代码中，在 main 中，调用函数onexit，该函数期望其参数 1 是带有指针的int。你应该喂一只int！
再来一次。您定义自己的函数onexit如下所示：
void onexit(int c, int s, FILE *fp, int flag);
您可以选择它希望参数 1 为int .然后，当您按如下方式调用它时：
onexit(NULL, sockd, NULL, 1);
您将其NULL作为参数 1 指定，这是一个指针，而不是int。
因此，编译器警告您它必须从指针生成整数。
顺便说一句，如果 rc 恰好为零，下面的代码片段会做一些令人讨厌的事情：
filename[rc] = ' ';
if (filename[strlen(filename)-1] == 'n')
filename[strlen(filename)-1] = ' ';
if (filename[strlen(filename)-1] == 'r')
filename[strlen(filename)-1] = ' ';
最好先检查 rc：
if (rc > 0 && filename[rc-1] == 'n') filename[--rc] = 0;
if (rc > 0 && filename[rc-1] == 'r') filename[--rc] = 0;
避免 2-4 次调用 strlen（） 也会为你节省一些周期。
为了避免缓冲区溢出（rc 可以等于文件名的大小），您可以使用
if((rc = recv(newsockd, filename, sizeof filename -1, 0)) < 0){...}