Handle unsuccessful fseek(…):s #13149

1. 
   practicalswift commented at 10:15 am on May 2, 2018: contributor

   Handle unsuccessful fseek(...):s.

   Note to reviewers: What is the most appropriate course of actions for each of these unsuccessful fseek(...):s?

2. Handle unsuccessful fseek(...):s 29c9bdcc14
3. fanquake added the label Refactoring on May 2, 2018
4. in src/util.cpp:891 in 29c9bdcc14 outdated

   886@@ -887,7 +887,9 @@ void AllocateFileRange(FILE *file, unsigned int offset, unsigned int length) {
   887     // Fallback version
   888     // TODO: just write one byte per block
   889     static const char buf[65536] = {};
   890-    fseek(file, offset, SEEK_SET);
   891+    if (fseek(file, offset, SEEK_SET)) {
   892+        return;
   

   ---

   ---

   

   laanwj commented at 1:35 pm on May 2, 2018:

   Just returning here is fine - this call is only advisory.
5. in src/logging.cpp:257 in 29c9bdcc14 outdated

   253@@ -254,7 +254,10 @@ void BCLog::Logger::ShrinkDebugFile()
   254     {
   255         // Restart the file with some of the end
   256         std::vector<char> vch(RECENT_DEBUG_HISTORY_SIZE, 0);
   257-        fseek(file, -((long)vch.size()), SEEK_END);
   258+        if (fseek(file, -((long)vch.size()), SEEK_END)) {
   

   ---

   ---

   

   laanwj commented at 1:36 pm on May 2, 2018:

   Not sure what should be done here. As-is it will silently fail to shrink the log file but should continue logging otherwise? Maybe log an error message?

   ---

   

   jonasschnelli commented at 6:27 am on May 3, 2018:

   Agree with @laanwj: an additional error message would make sense.
6. in src/index/txindex.cpp:272 in 29c9bdcc14 outdated

   267@@ -268,7 +268,9 @@ bool TxIndex::FindTx(const uint256& tx_hash, uint256& block_hash, CTransactionRe
   268     CBlockHeader header;
   269     try {
   270         file >> header;
   271-        fseek(file.Get(), postx.nTxOffset, SEEK_CUR);
   272+        if (fseek(file.Get(), postx.nTxOffset, SEEK_CUR)) {
   273+            return error("%s: fseek(...) failed", __func__);
   

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   laanwj commented at 1:37 pm on May 2, 2018:

   LGTM
7. laanwj approved
8. 
   jonasschnelli commented at 6:29 am on May 3, 2018: contributor

   utACK 29c9bdcc141afb14fc9e1213f49de4fcded6ce0c (though a LogPrint in ShrinkDebugFile() would be even better).
9. 
   practicalswift commented at 7:48 am on May 3, 2018: contributor

   @laanwj @jonasschnelli Regarding logging in ShrinkDebugFile(…) – what about the following:

    0diff --git a/src/logging.cpp b/src/logging.cpp
    1index 2a55d36..b57b17e 100644
    2--- a/src/logging.cpp
    3+++ b/src/logging.cpp
    4@@ -255,6 +255,7 @@ void BCLog::Logger::ShrinkDebugFile()
    5         // Restart the file with some of the end
    6         std::vector<char> vch(RECENT_DEBUG_HISTORY_SIZE, 0);
    7         if (fseek(file, -((long)vch.size()), SEEK_END)) {
    8+            LogPrintf("Failed to shrink debug file: fseek(...) failed\n");
    9             fclose(file);
   10             return;
   11         }
   

   Looks good?

10. 
    laanwj commented at 12:15 pm on May 3, 2018: member

    @practicalswift maybe “debug log file” instead of “debug file”?
11. Print a log message if we fail to shrink the debug log file 20ce5af4c6
12. 
    practicalswift commented at 1:44 pm on May 3, 2018: contributor

    @laanwj @jonasschnelli Added a commit for the logging. Please re-review :-)
13. jonasschnelli approved
14. 
    jonasschnelli commented at 1:46 pm on May 3, 2018: contributor

    utACK 20ce5af4c647d9ebd97b40683bd0747383c9dc20
15. 
    laanwj commented at 2:35 pm on May 3, 2018: member

    utACK 20ce5af
16. laanwj merged this on May 7, 2018
17. laanwj closed this on May 7, 2018

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Contributors
practicalswift laanwj jonasschnelli

Labels
Refactoring