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/* Split source by line breaks, and calculate a simplistic checksum. */
/*
* Copyright (c) 2020 Neels Hofmeyr <neels@hofmeyr.de>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <errno.h>
#include <setjmp.h>
#include <signal.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <ctype.h>
#include <arraylist.h>
#include <diff_main.h>
#include "diff_internal.h"
#include "diff_debug.h"
unsigned int
diff_atom_hash_update(unsigned int hash, unsigned char atom_byte)
{
return hash * 23 + atom_byte;
}
static int
diff_data_atomize_text_lines_fd(struct diff_data *d)
{
off_t pos = 0;
const off_t end = pos + d->len;
unsigned int array_size_estimate = d->len / 50;
unsigned int pow2 = 1;
bool ignore_whitespace = (d->diff_flags & DIFF_FLAG_IGNORE_WHITESPACE);
bool embedded_nul = false;
while (array_size_estimate >>= 1)
pow2++;
ARRAYLIST_INIT(d->atoms, 1 << pow2);
if (fseek(d->root->f, 0L, SEEK_SET) == -1)
return errno;
while (pos < end) {
off_t line_end = pos;
unsigned int hash = 0;
unsigned char buf[512];
size_t r, i;
struct diff_atom *atom;
int eol = 0;
while (eol == 0 && line_end < end) {
r = fread(buf, sizeof(char), sizeof(buf), d->root->f);
if (r == 0 && ferror(d->root->f))
return EIO;
i = 0;
while (eol == 0 && i < r) {
if (buf[i] != '\r' && buf[i] != '\n') {
if (!ignore_whitespace
|| !isspace((unsigned char)buf[i]))
hash = diff_atom_hash_update(
hash, buf[i]);
if (buf[i] == '\0')
embedded_nul = true;
line_end++;
} else
eol = buf[i];
i++;
}
}
/* When not at the end of data, the line ending char ('\r' or
* '\n') must follow */
if (line_end < end)
line_end++;
/* If that was an '\r', also pull in any following '\n' */
if (line_end < end && eol == '\r') {
if (fseeko(d->root->f, line_end, SEEK_SET) == -1)
return errno;
r = fread(buf, sizeof(char), sizeof(buf), d->root->f);
if (r == 0 && ferror(d->root->f))
return EIO;
if (r > 0 && buf[0] == '\n')
line_end++;
}
/* Record the found line as diff atom */
ARRAYLIST_ADD(atom, d->atoms);
if (!atom)
return ENOMEM;
*atom = (struct diff_atom){
.root = d,
.pos = pos,
.at = NULL, /* atom data is not memory-mapped */
.len = line_end - pos,
.hash = hash,
};
/* Starting point for next line: */
pos = line_end;
if (fseeko(d->root->f, pos, SEEK_SET) == -1)
return errno;
}
/* File are considered binary if they contain embedded '\0' bytes. */
if (embedded_nul)
d->atomizer_flags |= DIFF_ATOMIZER_FOUND_BINARY_DATA;
return DIFF_RC_OK;
}
static sigjmp_buf diff_data_signal_env;
static void
diff_data_signal_handler(int sig)
{
siglongjmp(diff_data_signal_env, sig);
}
static int
diff_data_atomize_text_lines_mmap(struct diff_data *d)
{
struct sigaction act, oact;
const uint8_t *volatile pos = d->data;
const uint8_t *end = pos + d->len;
bool ignore_whitespace = (d->diff_flags & DIFF_FLAG_IGNORE_WHITESPACE);
bool embedded_nul = false;
unsigned int array_size_estimate = d->len / 50;
unsigned int pow2 = 1;
while (array_size_estimate >>= 1)
pow2++;
ARRAYLIST_INIT(d->atoms, 1 << pow2);
sigemptyset(&act.sa_mask);
act.sa_flags = 0;
act.sa_handler = diff_data_signal_handler;
sigaction(SIGBUS, &act, &oact);
if (sigsetjmp(diff_data_signal_env, 0) > 0) {
/*
* The file was truncated while we were reading it. Set
* the end pointer to the beginning of the line we were
* trying to read, adjust the file length, and set a flag.
*/
end = pos;
d->len = end - d->data;
d->atomizer_flags |= DIFF_ATOMIZER_FILE_TRUNCATED;
}
while (pos < end) {
const uint8_t *line_start = pos, *line_end = pos;
unsigned int hash = 0;
while (line_end < end && *line_end != '\r' && *line_end != '\n') {
if (!ignore_whitespace
|| !isspace((unsigned char)*line_end))
hash = diff_atom_hash_update(hash, *line_end);
if (*line_end == '\0')
embedded_nul = true;
line_end++;
}
/* When not at the end of data, the line ending char ('\r' or
* '\n') must follow */
if (line_end < end && *line_end == '\r')
line_end++;
if (line_end < end && *line_end == '\n')
line_end++;
/* Record the found line as diff atom */
struct diff_atom *atom;
ARRAYLIST_ADD(atom, d->atoms);
if (!atom)
return ENOMEM;
*atom = (struct diff_atom){
.root = d,
.pos = (off_t)(line_start - d->data),
.at = line_start,
.len = line_end - line_start,
.hash = hash,
};
/* Starting point for next line: */
pos = line_end;
}
sigaction(SIGBUS, &oact, NULL);
/* File are considered binary if they contain embedded '\0' bytes. */
if (embedded_nul)
d->atomizer_flags |= DIFF_ATOMIZER_FOUND_BINARY_DATA;
return DIFF_RC_OK;
}
static int
diff_data_atomize_text_lines(struct diff_data *d)
{
if (d->data == NULL)
return diff_data_atomize_text_lines_fd(d);
else
return diff_data_atomize_text_lines_mmap(d);
}
int
diff_atomize_text_by_line(void *func_data, struct diff_data *d)
{
return diff_data_atomize_text_lines(d);
}
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