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zipl: fix Error when title is not the first field in BLS file

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Problem:
zipl implementation (specifically the scan code) implicitly
assumes that title field is always on the top of BLS file,
and this assumption doesn't comply the bootloader standards:
https://www.freedesktop.org/wiki/Specifications/BootLoaderSpec/

Solution:
Before parsing in-memory BLS entry, rearrange its lines as
following: search for a line with keyword "title" and move it
to the top. The scan code is invariant against such transform

Fixes: https://github.com/ibm-s390-tools/s390-tools/issues/64
Signed-off-by: Stefan Haberland <sth@linux.ibm.com>
Signed-off-by: Eduard Shishkin <edward6@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
This commit is contained in:
Eduard Shishkin
2020-08-24 11:36:21 +02:00
committed by Jan Höppner
parent 36bd05c4ba
commit 301eece09b
1 changed files with 67 additions and 0 deletions
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67
zipl/src/scan.c
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@@ -21,6 +21,7 @@
#define _GNU_SOURCE
#endif
#include <assert.h>
#include <ctype.h>
#include <dirent.h>
#include <errno.h>
@@ -28,6 +29,7 @@
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdbool.h>
#include <sys/stat.h>
@@ -730,6 +732,67 @@ scan_bls_field(struct misc_file_buffer *file, struct scan_token* scan,
return 0;
}
/**
* find a line with keyword "title" and move it to the top
*/
static int sort_bls_fields(struct misc_file_buffer *file, char *filename)
{
bool is_title = false;
size_t title_len = 0;
int nr_titles = 0;
size_t title_off;
char *title;
int current;
size_t len;
while (file->length - file->pos > 4 /* for "title" */) {
if (strncmp("title", &file->buffer[file->pos], 5) == 0) {
is_title = true;
nr_titles++;
title_off = file->pos;
}
for (len = 0;; file->pos++, len++) {
current = misc_get_char(file, 0);
if (current == '\n' || current == EOF)
break;
}
if (is_title == true)
title_len = len;
if (current == EOF)
break;
file->pos++;
}
file->pos = 0;
if (nr_titles == 0) {
error_reason("no title in %s", filename);
return -1;
}
if (nr_titles > 1) {
error_reason("more than one title in %s", filename);
return -1;
}
if (title_off == 0)
return 0;
title = misc_malloc(title_len);
if (!title)
return -1;
/*
* copy the title field w/o trailing '\n' to the temporary buffer
*/
memcpy(title, &file->buffer[title_off], title_len);
/*
* shift preceded memory region w/o trailing '\n' to the right
*/
assert(file->buffer[title_off - 1] == '\n');
memmove(&file->buffer[title_len + 1], &file->buffer[0], title_off - 1);
file->buffer[title_len] = '\n';
memcpy(&file->buffer[0], title, title_len);
free(title);
return 0;
}
int
scan_bls(const char* blsdir, struct scan_token** token, int scan_size)
@@ -780,6 +843,10 @@ scan_bls(const char* blsdir, struct scan_token** token, int scan_size)
if (rc)
goto err;
rc = sort_bls_fields(&file, filename);
if (rc)
goto err;
while ((size_t)file.pos < file.length) {
current = misc_get_char(&file, 0);
switch (current) {