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Add missing_ok option to the SQL functions for reading files.

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This makes it possible to use the functions without getting errors, if there
is a chance that the file might be removed or renamed concurrently.
pg_rewind needs to do just that, although this could be useful for other
purposes too. (The changes to pg_rewind to use these functions will come in
a separate commit.)

The read_binary_file() function isn't very well-suited for extensions.c's
purposes anymore, if it ever was. So bite the bullet and make a copy of it
in extension.c, tailored for that use case. This seems better than the
accidental code reuse, even if it's a some more lines of code.

Michael Paquier, with plenty of kibitzing by me.
This commit is contained in:
Heikki Linnakangas
2015-06-28 21:35:46 +03:00
parent cca8ba9529
commit cb2acb1081
6 changed files with 274 additions and 102 deletions
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69
src/backend/commands/extension.c
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@ -25,6 +25,8 @@
#include <dirent.h>
#include <limits.h>
#include <sys/file.h>
#include <sys/stat.h>
#include <unistd.h>
#include "access/htup_details.h"
@ -51,6 +53,7 @@
#include "utils/builtins.h"
#include "utils/fmgroids.h"
#include "utils/lsyscache.h"
#include "utils/memutils.h"
#include "utils/rel.h"
#include "utils/snapmgr.h"
#include "utils/tqual.h"
@ -103,6 +106,7 @@ static void ApplyExtensionUpdates(Oid extensionOid,
ExtensionControlFile *pcontrol,
const char *initialVersion,
List *updateVersions);
static char *read_whole_file(const char *filename, int *length);
/*
@ -635,12 +639,11 @@ read_extension_script_file(const ExtensionControlFile *control,
const char *filename)
{
int src_encoding;
bytea *content;
char *src_str;
char *dest_str;
int len;
content = read_binary_file(filename, 0, -1);
src_str = read_whole_file(filename, &len);
/* use database encoding if not given */
if (control->encoding < 0)
@ -649,21 +652,15 @@ read_extension_script_file(const ExtensionControlFile *control,
src_encoding = control->encoding;
/* make sure that source string is valid in the expected encoding */
len = VARSIZE_ANY_EXHDR(content);
src_str = VARDATA_ANY(content);
pg_verify_mbstr_len(src_encoding, src_str, len, false);
/* convert the encoding to the database encoding */
/*
* Convert the encoding to the database encoding. read_whole_file
* null-terminated the string, so if no conversion happens the string is
* valid as is.
*/
dest_str = pg_any_to_server(src_str, len, src_encoding);
/* if no conversion happened, we have to arrange for null termination */
if (dest_str == src_str)
{
dest_str = (char *) palloc(len + 1);
memcpy(dest_str, src_str, len);
dest_str[len] = '\0';
}
return dest_str;
}
@ -3008,3 +3005,49 @@ ExecAlterExtensionContentsStmt(AlterExtensionContentsStmt *stmt,
return extension;
}
/*
* Read the whole of file into memory.
*
* The file contents are returned as a single palloc'd chunk. For convenience
* of the callers, an extra \0 byte is added to the end.
*/
static char *
read_whole_file(const char *filename, int *length)
{
char *buf;
FILE *file;
size_t bytes_to_read;
struct stat fst;
if (stat(filename, &fst) < 0)
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not stat file \"%s\": %m", filename)));
if (fst.st_size > (MaxAllocSize - 1))
ereport(ERROR,
(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
errmsg("file too large")));
bytes_to_read = (size_t) fst.st_size;
if ((file = AllocateFile(filename, PG_BINARY_R)) == NULL)
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not open file \"%s\" for reading: %m",
filename)));
buf = (char *) palloc(bytes_to_read + 1);
*length = fread(buf, 1, bytes_to_read, file);
if (ferror(file))
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not read file \"%s\": %m", filename)));
FreeFile(file);
buf[*length] = '\0';
return buf;
}