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Fix lo_import and lo_export to return useful error messages more often.

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I found that these functions tend to return -1 while leaving an empty error
message string in the PGconn, if they suffer some kind of I/O error on the
file.  The reason is that lo_close, which thinks it's executed a perfectly
fine SQL command, clears the errorMessage.  The minimum-change workaround
is to reorder operations here so that we don't fill the errorMessage until
after lo_close.
This commit is contained in:
Tom Lane 2012-10-08 21:52:42 -04:00
parent cf9d99298c
commit c5b8daa08d
1 changed files with 24 additions and 9 deletions
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33
src/interfaces/libpq/fe-lobj.c
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@ -569,10 +569,16 @@ lo_import_internal(PGconn *conn, const char *filename, Oid oid)
if (nbytes < 0) if (nbytes < 0)
{ {
/* We must do lo_close before setting the errorMessage */
int save_errno = errno;
(void) lo_close(conn, lobj);
(void) close(fd);
printfPQExpBuffer(&conn->errorMessage, printfPQExpBuffer(&conn->errorMessage,
libpq_gettext("could not read from file \"%s\": %s\n"), libpq_gettext("could not read from file \"%s\": %s\n"),
filename, pqStrerror(errno, sebuf, sizeof(sebuf))); filename,
lobjOid = InvalidOid; pqStrerror(save_errno, sebuf, sizeof(sebuf)));
return InvalidOid;
} }
(void) close(fd); (void) close(fd);
@ -617,11 +623,15 @@ lo_export(PGconn *conn, Oid lobjId, const char *filename)
*/ */
fd = open(filename, O_CREAT | O_WRONLY | O_TRUNC | PG_BINARY, 0666); fd = open(filename, O_CREAT | O_WRONLY | O_TRUNC | PG_BINARY, 0666);
if (fd < 0) if (fd < 0)
{ /* error */ {
/* We must do lo_close before setting the errorMessage */
int save_errno = errno;
(void) lo_close(conn, lobj);
printfPQExpBuffer(&conn->errorMessage, printfPQExpBuffer(&conn->errorMessage,
libpq_gettext("could not open file \"%s\": %s\n"), libpq_gettext("could not open file \"%s\": %s\n"),
filename, pqStrerror(errno, sebuf, sizeof(sebuf))); filename,
(void) lo_close(conn, lobj); pqStrerror(save_errno, sebuf, sizeof(sebuf)));
return -1; return -1;
} }
@ -633,11 +643,15 @@ lo_export(PGconn *conn, Oid lobjId, const char *filename)
tmp = write(fd, buf, nbytes); tmp = write(fd, buf, nbytes);
if (tmp != nbytes) if (tmp != nbytes)
{ {
printfPQExpBuffer(&conn->errorMessage, /* We must do lo_close before setting the errorMessage */
libpq_gettext("could not write to file \"%s\": %s\n"), int save_errno = errno;
filename, pqStrerror(errno, sebuf, sizeof(sebuf)));
(void) lo_close(conn, lobj); (void) lo_close(conn, lobj);
(void) close(fd); (void) close(fd);
printfPQExpBuffer(&conn->errorMessage,
libpq_gettext("could not write to file \"%s\": %s\n"),
filename,
pqStrerror(save_errno, sebuf, sizeof(sebuf)));
return -1; return -1;
} }
} }
@ -655,7 +669,8 @@ lo_export(PGconn *conn, Oid lobjId, const char *filename)
result = -1; result = -1;
} }
if (close(fd)) /* if we already failed, don't overwrite that msg with a close error */
if (close(fd) && result >= 0)
{ {
printfPQExpBuffer(&conn->errorMessage, printfPQExpBuffer(&conn->errorMessage,
libpq_gettext("could not write to file \"%s\": %s\n"), libpq_gettext("could not write to file \"%s\": %s\n"),