Bug#911931: kcachegrind gives confusing and wrong error message for valgridn files with long commandlines

[Marc Lehmann <debian-reportbug@plan9.de>]

Package: kcachegrind
Version: 4:17.08.3-2
Severity: normal

Dear Maintainer,

when opening a cachegrind file generated with valgrind, kcachegrind failed to open the file
with the following message:

   Could not open file "cachegrind.out.2772". Check it exists and you have enough permissions to read it.

strace showed that kcachegrind was able to open the file. The real reason,
as it turned out, was that the commandline was very long (the result of
expanding a directory full of tcpdumps with *, generating a 1MB command
line).

Manually editing the file to shorten the command line in the file made
kcachegrind load the file.

AFAICS, there are two bugs here:

1) kcachegrind giving a wrong and confusing error message (apparently, it was able to open
the file just fine, but then failed to parse the contents).

2) kcachegrind not being able to parse the output of valgrind (which is
the main purpose it was written for)

Obviously, kcachegrind could use a better error message, and more
importantly, should be able to parse the valgrind output.

-- System Information:
Debian Release: 9.5
  APT prefers stable
  APT policy: (990, 'stable'), (500, 'unstable-debug'), (500, 'testing-debug'), (500, 'stable-updates'), (500, 'stable-debug'), (500, 'unstable'), (500, 'testing'), (1, 'experimental-debug'), (1, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 4.14.73-041473-generic (SMP w/8 CPU cores)
Locale: LANG=C, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE=C (charmap=UTF-8)
Shell: /bin/sh linked to /usr/bin/bash
Init: systemd (via /run/systemd/system)

Versions of packages kcachegrind depends on:
ii  kio                   5.28.0-2
ii  libc6                 2.27-6
ii  libkf5archive5        5.28.0-2
ii  libkf5configcore5     5.28.0-2
ii  libkf5configwidgets5  5.28.0-2
ii  libkf5coreaddons5     5.28.0-2
ii  libkf5i18n5           5.28.0-2
ii  libkf5jobwidgets5     5.28.0-2
ii  libkf5kiocore5        5.28.0-2
ii  libkf5widgetsaddons5  5.28.0-3
ii  libkf5xmlgui5         5.28.0-1
ii  libqt5core5a          5.11.2+dfsg-3
ii  libqt5dbus5           5.11.2+dfsg-3
ii  libqt5gui5            5.11.2+dfsg-3
ii  libqt5widgets5        5.11.2+dfsg-3
ii  libstdc++6            8.2.0-8

Versions of packages kcachegrind recommends:
ii  graphviz  2.38.0-17
ii  valgrind  1:3.13.0-2.1

Versions of packages kcachegrind suggests:
ii  kcachegrind-converters  4:16.08.3-1
ii  khelpcenter             4:16.08.3-1

-- no debconf information