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tweaks: harmonize the amount of lock data that we read and write

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All the things that we need are located within the first 68 bytes of
the .swp file.  We do write byte 1007 when the file is modified, but
we never reference it.  We always wrote just 1024 bytes to the .swp
file, so it makes no sense to read in any more than that.

(Vim writes 4096 bytes to a .swp at first, before adding undo stuff
four seconds later.  But the 1024 bytes appear to be enough for Vim
to recognize it as a lock file.)
This commit is contained in:
Benno Schulenberg 2020-01-31 11:06:11 +01:00
parent 6bd5dce954
commit 5a0ee3c2f9
1 changed files with 9 additions and 10 deletions
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19
src/files.c
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@ -31,7 +31,7 @@
#include <unistd.h>
#ifndef NANO_TINY
#define LOCKBUFSIZE 8192
#define LOCKSIZE 1024
const char *locking_prefix = ".";
const char *locking_suffix = ".swp";
/* Prefix and suffix for the name of the vim-style lock file. */
@ -171,9 +171,8 @@ int write_lockfile(const char *lockfilename, const char *origfilename, bool modi
uid_t myuid;
struct passwd *mypwuid;
struct stat fileinfo;
char *lockdata = charalloc(1024);
char *lockdata = charalloc(LOCKSIZE);
char myhostname[32];
size_t lockdatalen = 1024;
size_t wroteamt;
mypid = getpid();
@ -240,7 +239,7 @@ int write_lockfile(const char *lockfilename, const char *origfilename, bool modi
* Nano also does not use all available space for user name (40 bytes),
* host name (40 bytes), and file name (890 bytes). Nor does nano write
* some byte-order-checking numbers (bytes 1008-1022). */
memset(lockdata, 0, lockdatalen);
memset(lockdata, 0, LOCKSIZE);
lockdata[0] = 0x62;
lockdata[1] = 0x30;
snprintf(&lockdata[2], 10, "nano %s", VERSION);
@ -255,9 +254,9 @@ int write_lockfile(const char *lockfilename, const char *origfilename, bool modi
if (modified == TRUE)
lockdata[1007] = 0x55;
wroteamt = fwrite(lockdata, sizeof(char), lockdatalen, filestream);
wroteamt = fwrite(lockdata, sizeof(char), LOCKSIZE, filestream);
if (wroteamt < lockdatalen) {
if (wroteamt < LOCKSIZE) {
statusline(MILD, _("Error writing lock file %s: %s"),
lockfilename, ferror(filestream));
fclose(filestream);
@ -326,16 +325,16 @@ int do_lockfile(const char *filename, bool ask_the_user)
goto free_the_name;
}
lockbuf = charalloc(LOCKBUFSIZE);
lockbuf = charalloc(LOCKSIZE);
do {
readamt = read(lockfd, &lockbuf[readtot], LOCKBUFSIZE - readtot);
readamt = read(lockfd, &lockbuf[readtot], LOCKSIZE - readtot);
readtot += readamt;
} while (readamt > 0 && readtot < LOCKBUFSIZE);
} while (readamt > 0 && readtot < LOCKSIZE);
close(lockfd);
if (readtot < 1024 || lockbuf[0] != 0x62 || lockbuf[1] != 0x30) {
if (readtot < LOCKSIZE || lockbuf[0] != 0x62 || lockbuf[1] != 0x30) {
statusline(ALERT, _("Bad lock file is ignored: %s"), lockfilename);
free(lockbuf);
goto free_the_name;