系统调用“打开".无法使用O_CREAT标志创建文件

P.S.: To highlight I'm using syscalls, I'm not calling function open(...) but syscall(SYS_OPEN, ...)outFileDesc = syscall(SYS_OPEN, "testoutput.txt", O_WRONLY | O_TRUNC | O_CREAT, 438);if(outFileDesc == -1) { int code = errno; // gdb used here -> print code -> 2 char str[] = "Unable to open \"testoutput.txt\"\n"; syscall(SYS_WRITE, FILE_DESC_STDOUT, str, sizeof(str)/sizeof(char)); syscall(SYS_CLOSE, inFileDesc); syscall(SYS_EXIT, 1); return 1; }整个代码:#include <unistd.h>#include <sys/syscall.h>#include <errno.h>/* file flags fcntl.h */#define O_RDONLY 0x0000 /* open for reading only */#define O_WRONLY 0x0001 /* open for writing only */#define O_CREAT 0x0200 /* create if nonexistant */#define O_TRUNC 0x0400 /* truncate to zero length */#define FILE_DESC_STDOUT 1#define SYS_EXIT 1#define SYS_READ 3#define SYS_WRITE 4#define SYS_OPEN 5#define SYS_CLOSE 6#define IN_MESSAGE_LEN 9#define OUT_MESSAGE_LEN 9char inBuffer[IN_MESSAGE_LEN];char outBuffer[OUT_MESSAGE_LEN];int main (int argc, char *argv[]){ int inFileDesc, outFileDesc; // Apertura fine di input inFileDesc = syscall(SYS_OPEN, "testinput.txt", O_RDONLY, 438); if(inFileDesc == -1) { char str[] = "Unable to open \"testinput.txt\"\n"; syscall(SYS_WRITE, FILE_DESC_STDOUT, str, sizeof(str)/sizeof(char)); syscall(SYS_EXIT, 1); return 1; } // Apertura fine di output outFileDesc = syscall(SYS_OPEN, "testoutput.txt", O_WRONLY | O_TRUNC | O_CREAT, 438); if(outFileDesc == -1) { int code = errno; char str[] = "Unable to open \"testoutput.txt\"\n"; syscall(SYS_WRITE, FILE_DESC_STDOUT, str, sizeof(str)/sizeof(char)); syscall(SYS_CLOSE, inFileDesc); syscall(SYS_EXIT, 1); return 1; } // Travaso contenuto file di input in file di output int read, i; while((read = syscall(SYS_READ, inFileDesc, inBuffer, IN_MESSAGE_LEN)) != 0) { for(i = 0; i < IN_MESSAGE_LEN; i++) { outBuffer[i] = inBuffer[i]; } syscall(SYS_WRITE, outFileDesc, outBuffer, OUT_MESSAGE_LEN); } syscall(SYS_CLOSE, inFileDesc); syscall(SYS_CLOSE, outFileDesc); syscall(SYS_EXIT, 0); return 0;} 推荐答案我在 strace 并得到:I ran your code under strace and got:...open("testinput.txt", O_RDONLY) = 3open("testoutput.txt", O_WRONLY|O_TRUNC|O_APPEND) = -1 ENOENT (No such file or directory)// ^^^^^^^^即您对 O _ * 标志的定义是错误的.I.e. your definition of the O_* flags is wrong.事实证明，不只一个错误: 0x0200 实际上是 O_TRUNC (不是 O_CREAT )，而 0x0400实际上是 O_APPEND (不是 O_TRUNC ).As it turns out, there's more than one thing wrong: 0x0200 is actually O_TRUNC (not O_CREAT), and 0x0400 is actually O_APPEND (not O_TRUNC).更改为#define O_CREAT 0x0040#define O_TRUNC 0x0200使其正常工作. 这篇关于系统调用“打开".无法使用O_CREAT标志创建文件的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！