我正试图让我的一些通过 bash 重定向记录的应用程序变得非常容易登录。基本上，我有一个将 STDIN 读入缓冲区的 C 程序。它读取此缓冲区，并且每当遇到换行符时，它将收集到的输出写入文件。
该程序的不同之处在于它不会使文件保持打开状态。每次遇到新行时，它都会打开它以进行追加。这与 logrotate 实用程序配合得很好，但我想知道是否存在某种可怕的不可预见的问题，我没有考虑到稍后会遇到的问题。
仅在此实用程序中实现信号处理并让 logrotate 向其发送 SIGHUP 会更好吗？我正在做的事情有可怕的性能损失吗？
所以通常你会在哪里做：
./app >> output.log
使用记录器实用程序，您可以：
./app | ./mylogger output.log
虽然我的 C 语言太差了，但我并不十分精通它的最佳实践。任何指导将不胜感激。
这是来源：
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#define BUFSIZE 1024
#define MAX_WRITE_FAILS 3
/**
* outputs the given content to the specified file.
*/
int file_output(char *filename, char *content, size_t content_length)
{
FILE *fp;
fp = fopen(filename, "a");
content[content_length + 1] = '\0';
if(fp == NULL) return errno;
fwrite(content, sizeof(char), content_length, fp);
fclose(fp);
return 0;
}
/**
* Loops over STDIN and whenever it finds a newline, sends the current content
* buffer to the file specified on the command line.
*/
int main(int argc, char *argv[])
{
int i;
char buffer[BUFSIZE];
char *content = malloc(sizeof(char) * BUFSIZE);
size_t content_size = 0;
int content_buf_size = BUFSIZE;
int write_failures = 0;
char *file;
if(argc < 2)
{
fprintf(stderr, "Usage: logger <file>");
exit(1);
}
file = argv[1];
// loop over STDIN
while(fgets(buffer, BUFSIZE, stdin))
{
int output_err;
int buflength = strlen(buffer);
// loop over character for character, searching for newlines and
// appending our buffer to the output content as we go along
for(i = 0; i < buflength; i++)
{
char *old = content;
// check if we have a newline or end of string
if(buffer[i] == '\n' || buffer[i] == '\0' || (i != (buflength - 1) && buffer[i] == '\r' && buffer[i+1] == '\n'))
{
content[content_size] = '\n';
output_err = file_output(file, content, content_size + 1);
if(output_err == 0)
{
// success! reset the content size (ie more or less resets
// the output content string)
content_size = 0;
write_failures = 0;
}
else
{
// write failed, try to keep going. this will preserve our
// newline so that the next newline we encounter will write
// both lines (this AND and the next).
content_size++;
write_failures++;
}
}
if(write_failures >= MAX_WRITE_FAILS)
{
fprintf(stderr, "Failed to write output to file %d times (errno: %d). Quitting.\n", write_failures, output_err);
exit(3);
}
if(buffer[i] != '\n' && buffer[i] != '\r' && buffer[i] != '\0')
{
// copy buffer into content (if it's not a newline/null)
content[content_size] = buffer[i];
content_size++;
}
// check if we're pushing the limits of our content buffer
if(content_size >= content_buf_size - 1)
{
// we need to up the size of our output buffer
content_buf_size += BUFSIZE;
content = (char *)realloc(content, sizeof(char) * content_buf_size);
if(content == NULL)
{
fprintf(stderr, "Failed to reallocate buffer memory.\n");
free(old);
exit(2);
}
}
}
}
return 0;
}
谢谢！