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| #define _XOPEN_SOURCE 600
#include <string.h>
#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#include <stdbool.h>
#include <unistd.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/types.h>
#include <stdarg.h>
#define INFO(msg, ...) fprintf(stderr, "INFO: ");\
fprintf(stderr, msg, ##__VA_ARGS__)
#define CHECK(flag, msg, ...) do { \
if(!(flag)) {\
fprintf(stderr, "FATAL: "); \
fprintf(stderr, msg, ##__VA_ARGS__); \
fprintf(stderr, " ERROR: %s\n", strerror(errno)); \
exit(2); \
} \
} while(0)
#define streq(str1, str2) (strcmp(str1, str2)==0)
#ifndef BUFSIZE
#define BUFSIZE 1
#endif
bool str2int(const char *num, int *ret) {
errno = 0;
char *end;
*ret = strtol(num, &end, 10);
CHECK(!(end == num || *end != '\0' || errno != 0), "%s is not a integer!\n", num);
return true;
}
void print(const char *str, ...) {
va_list list;
va_start(list, str);
for(const char *s = str; s != NULL; (s = va_arg(list, const char *))) {
size_t slen = va_arg(list, size_t);
ssize_t wsize = write(STDOUT_FILENO, s, slen);
CHECK(wsize == slen, "fail to print %s\n", s);
}
va_end(list);
}
char *str_alloc_reverse_cat(char * str1, const char *str2, int *len1, int len2) {
char *str = realloc(strdup(str2), (*len1+len2+1) * sizeof(char));
str[len2] = 0;
strncat(str, str1, *len1);
*len1 += len2;
return str;
}
void tail(int fd, const int line, off_t end) {
int num = line;
char *buf = (char*)malloc((BUFSIZE+1)*sizeof(char));
char **output = (char **)malloc(num *sizeof(char *));
int *output_len = (int *) malloc(num * sizeof(int));
memset(output, 0, num *sizeof(char *));
memset(output_len, 0, num *sizeof(int));
while(end > 0 && num) {
size_t bufsize = BUFSIZE > end ? end : BUFSIZE;
posix_fadvise(fd, end-bufsize, bufsize, POSIX_FADV_WILLNEED);
CHECK(end != -1, "end = %ld, fail to lseek fd%d", end, fd);
ssize_t readsize = pread(fd, buf, bufsize, end-bufsize);
CHECK(readsize >= 0, "readsize = %ld, fail to read fd%d", readsize, fd);
buf[readsize] = 0;
end -= bufsize;
CHECK(end != -1, "end = %ld, fail to lseek fd%d", end, fd);
while(readsize >= 0 && num) {
ssize_t move = readsize-1;
while(move >=0 && buf[move] != '\n') move--;
size_t size = readsize - move - 1;
if(move >= 0 || end == 0) {
num--;
output[num] = str_alloc_reverse_cat(output[num], buf+move+1, &output_len[num], size);
} else {
output[num-1] = str_alloc_reverse_cat(output[num-1], buf+move+1, &output_len[num-1], size);
}
readsize = move;
}
}
size_t outbufsize = 1;
for(int i = num; i < line; i++) {
outbufsize += output_len[i]+1;
}
char *outbuf = (char *) malloc(outbufsize*sizeof(char));
outbuf[0] = 0;
for(int i = num; i < line; i++) {
strcat(outbuf, output[i]);
strcat(outbuf, "\n");
free(output[i]);
}
print(outbuf, outbufsize - 1, NULL);
free(outbuf);
free(buf);
free(output);
}
char *str_alloc_cat(char * str1, const char *str2, int *len1, int len2) {
char *str = NULL;
if(str1 == NULL) {
str = malloc((*len1+len2+1) * sizeof(char));
*len1 = 0;
} else {
str = realloc(str1, (*len1 + len2 + 1) * sizeof(char));
}
str[*len1] = 0;
strncat(str + *len1, str2, len2);
*len1 += len2;
return str;
}
void tailsafe(int fd, const int num) {
int line = 0;
char *buf = (char*)malloc((BUFSIZE+1)*sizeof(char));
char **output = (char **)malloc(num *sizeof(char *));
int *output_len = (int *) malloc(num * sizeof(int));
memset(output, 0, num *sizeof(char *));
memset(output_len, 0, num *sizeof(int));
size_t readsize = 0, prev_readsize = 0;
int i,j;
while((readsize = read(fd, buf, BUFSIZE)) != 0) {
prev_readsize = readsize;
CHECK(readsize >= 0, "readsize = %ld, fail to read fd%d", readsize, fd);
buf[readsize] = 0;
for(i = 0; i < readsize; i=j+1) {
j = i;
while(j < readsize && buf[j] != '\n')j++;
if(output[line] != NULL && output[line][output_len[line]] == '\n') {
free(output[line]);
output[line]= NULL;
}
if(j < readsize) {
output[line] = str_alloc_cat(output[line], buf+i, &output_len[line], j - i);
output[line][output_len[line]] = '\n';
line = (line+1)%num;
} else {
output[line] = str_alloc_cat(output[line], buf+i, &output_len[line], j - i);
break;
}
}
}
if(i < prev_readsize) {
output[line][output_len[line]] = 0;
line = (line+1)%num;
}
if(output[line] == NULL) {
line = 0;
}
size_t outbufsize = 1;
for(int i = 0; i < num; i++) {
outbufsize += output_len[i]+1;
if(output[i] != NULL) output[i][output_len[i]] = 0;
}
char *outbuf = (char *) malloc(outbufsize*sizeof(char));
outbuf[0] = 0;
for(int i = 0; i < num && output[(i+line)%num] != NULL; i++) {
strcat(outbuf, output[(i+line)%num]);
strcat(outbuf, "\n");
free(output[(i+line)%num]);
}
print(outbuf, outbufsize - 1, NULL);
free(outbuf);
free(output_len);
free(output);
free(buf);
}
int main(int argc, char ** argv) {
char **filename = (char **)malloc(argc * sizeof(char *));
int filecount = 0;
int num = 10;
bool safe = false;
for(int i = 1; i < argc; i++) {
if(argv[i][0] == '-') {
if(streq(argv[i], "--help") || streq(argv[i], "-h")) {
INFO("Usage: %s [-h|--help] [-n num] filename", argv[0]);
} else if(streq(argv[i], "-n")) {
str2int(argv[++i], &num);
} else if(streq(argv[i], "--safe")) {
safe = true;
}
} else {
filename[filecount++] = strdup(argv[i]);
}
}
CHECK(num >= 0, "num should be non-negative, num = %d\n", num);
if(filecount == 0) {
INFO("Usage: %s [-h|--help] [-n num] filename", argv[0]);
}
for(int i = 0; i < filecount; i++) {
int fd = open(filename[i], O_RDONLY);
CHECK(fd != -1, "fail to open %s, fd = %d", filename[i], fd);
if (filecount > 1) print("==> ", 4, filename[i], strlen(filename[i]), " <==", 4, "\n", 1, NULL);
if(!safe) {
off_t pos = lseek(fd, 0, SEEK_END);
CHECK(pos != -1, "fail to lseek %s, pos = %ld", filename[i], pos);
tail(fd, num, pos);
} else {
tailsafe(fd, num);
}
close(fd);
free(filename[i]);
}
free(filename);
return 0;
}
|