line_buffer.c

   1 #include <stdio.h>
   2 #include <stdlib.h>
   3 #include <string.h>
   4
   5 #include "line_buffer.h"
   6
   7 #define LINE_BUFFER_LEN 10000
   8 #define COPY_BUFFER_LEN 4096
   9
  10 static char line_buffer[LINE_BUFFER_LEN];
  11 static uint32_t line_buffer_len = 0;
  12 static uint32_t line_len = 0;
  13
  14 char *buffer_read_line(void)
  15 {
  16     char *end;
  17     uint32_t n_read;
  18
  19     if (line_len) {
  20         memmove(line_buffer, &line_buffer[line_len],
  21                 line_buffer_len - line_len);
  22         line_buffer_len -= line_len;
  23         line_len = 0;
  24     }
  25
  26     end = memchr(line_buffer, '\n', line_buffer_len);
  27     while (line_buffer_len < LINE_BUFFER_LEN - 1 &&
  28            !feof(stdin) && NULL == end) {
  29         n_read =
  30             fread(&line_buffer[line_buffer_len], 1,
  31                   LINE_BUFFER_LEN - 1 - line_buffer_len,
  32                   stdin);
  33         end = memchr(&line_buffer[line_buffer_len], '\n', n_read);
  34         line_buffer_len += n_read;
  35     }
  36
  37     if (ferror(stdin))
  38         return NULL;
  39
  40     if (end != NULL) {
  41         line_len = end - line_buffer;
  42         line_buffer[line_len++] = '\0';
  43     } else {
  44         line_len = line_buffer_len;
  45         line_buffer[line_buffer_len] = '\0';
  46     }
  47
  48     if (line_len == 0)
  49         return NULL;
  50
  51     return line_buffer;
  52 }
  53
  54 char *buffer_read_string(uint32_t len)
  55 {
  56     char *s = malloc(len + 1);
  57     uint32_t offset = 0;
  58     if (line_buffer_len > line_len) {
  59         offset = line_buffer_len - line_len;
  60         if (offset > len)
  61             offset = len;
  62         memcpy(s, &line_buffer[line_len], offset);
  63         line_len += offset;
  64     }
  65     while (offset < len && !feof(stdin)) {
  66         offset += fread(&s[offset], 1, len - offset, stdin);
  67     }
  68     s[offset] = '\0';
  69     return s;
  70 }
  71
  72 static char byte_buffer[COPY_BUFFER_LEN];
  73 void buffer_copy_bytes(uint32_t len)
  74 {
  75     uint32_t in, out;
  76     if (line_buffer_len > line_len) {
  77         in = line_buffer_len - line_len;
  78         if (in > len)
  79             in = len;
  80         out = 0;
  81         while (out < in && !ferror(stdout)) {
  82             out +=
  83                 fwrite(&line_buffer[line_len + out], 1, in - out, stdout);
  84         }
  85         len -= in;
  86         line_len += in;
  87     }
  88     while (len > 0 && !feof(stdin)) {
  89         in = len < COPY_BUFFER_LEN ? len : COPY_BUFFER_LEN;
  90         in = fread(byte_buffer, 1, in, stdin);
  91         len -= in;
  92         out = 0;
  93         while (out < in && !ferror(stdout)) {
  94             out += fwrite(&byte_buffer[out], 1, in - out, stdout);
  95         }
  96     }
  97 }
  98
  99 void buffer_skip_bytes(uint32_t len)
 100 {
 101     uint32_t in;
 102     if (line_buffer_len > line_len) {
 103         in = line_buffer_len - line_len;
 104         if (in > len)
 105             in = len;
 106         line_len += in;
 107         len -= in;
 108     }
 109     while (len > 0 && !feof(stdin)) {
 110         in = len < COPY_BUFFER_LEN ? len : COPY_BUFFER_LEN;
 111         in = fread(byte_buffer, 1, in, stdin);
 112         len -= in;
 113     }
 114 }
 115