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08 Apr 2020 10:24:03 +0200 To: qemu-devel@nongnu.org From: Brice Goglin Subject: linux-user: keep the name-ending parenthesis in /proc/self/stat Autocrypt: addr=Brice.Goglin@inria.fr; prefer-encrypt=mutual; keydata= mQINBFNg91oBEADMfOyfz9iilNPe1Yy3pheXLf5O/Vpr+gFJoXcjA80bMeSWBf4on8Mt5Fg/ jpVuNBhii0Zyq4Lip1I2ve+WQjfL3ixYQqvNRLgfw/FL0gNHSOe9dVFo0ol0lT+vu3AXOVmh AM4IrsOp2Tmt+w89Oyvu+xwHW54CJX3kXp4c7COz79A6OhbMEPQUreerTavSvYpH5pLY55WX qOSdjmlXD45yobQbMg9rFBy1BECrj4DJSpym/zJMFVnyC5yAq2RdPFRyvYfS0c491adD/iw9 eFZY1XWj+WqLSW8zEejdl78npWOucfin7eAKvov5Bqa1MLGS/2ojVMHXJN0qpStpKcueV5Px igX8i4O4pPT10xCXZ7R6KIGUe1FE0N7MLErLvBF6AjMyiFHix9rBG0pWADgCQUUFjc8YBKng nwIKl39uSpk5W5rXbZ9nF3Gp/uigTBNVvaLO4PIDw9J3svHQwCB31COsUWS1QhoLMIQPdUkk GarScanm8i37Ut9G+nB4nLeDRYpPIVBFXFD/DROIEfLqOXNbGwOjDd5RWuzA0TNzJSeOkH/0 qYr3gywjiE81zALO3UeDj8TaPAv3Dmu7SoI86Bl7qm6UOnSL7KQxZWuMTlU3BF3d+0Ly0qxv k1XRPrL58IyoHIgAVom0uUnLkRKHczdhGDpNzsQDJaO71EPp8QARAQABtCRCcmljZSBHb2ds aW4gPEJyaWNlLkdvZ2xpbkBpbnJpYS5mcj6JAjgEEwECACIFAlNg+aMCGwMGCwkIBwMCBhUI AgkKCwQWAgMBAh4BAheAAAoJEESRkPMjWr076RoQAJhJ1q5+wlHIf+YvM0N1V1hQyf+aL35+ BPqxlyw4H65eMWIN/63yWhcxrLwNCdgY1WDWGoiW8KVCCHwJAmrXukFvXjsvShLQJavWRgKH eea12T9XtLc6qY/DEi2/rZvjOCKsMjnc1CYW71jbofaQP6lJsmC+RPWrnL/kjZyVrVrg7/Jo GemLmi/Ny7nLAOt6uL0MC/Mwld14Yud57Qz6VTDGSOvpNacbkJtcCwL3KZDBfSDnZtSbeclY srXoMnFXEJJjKJ6kcJrZDYPrNPkgFpSId/WKJ5pZBoRsKH/w2OdxwtXKCYHksMCiI4+4fVFD WlmVNYzW8ZKXjAstLh+xGABkLVXs+0WjvC67iTZBXTmbYJ5eodv8U0dCIR/dxjK9wxVKbIr2 D+UVbGlfqUuh1zzL68YsOg3L0Xc6TQglKVl6RxX87fCU8ycIs9pMbXeRDoJohflo8NUDpljm zqGlZxBjvb40p37ReJ+VfjWqAvVh+6JLaMpeva/2K1Nvr9O/DOkSRNetrd86PslrIwz8yP4l FaeG0dUwdRdnToNz6E8lbTVOwximW+nwEqOZUs1pQNKDejruN7Xnorr7wVBfp6zZmFCcmlw9 8pSMV3p85wg6nqJnBkQNTzlljycBvZLVvqc6hPOSXpXf5tjkuUVWgtbCc8TDEQFx8Phkgda6 K1LNuQINBFNg91oBEADp3vwjw8tQBnNfYJNJMs6AXC8PXB5uApT1pJ0fioaXvifPNL6gzsGt AF53aLeqB7UXuByHr8Bmsz7BvwA06XfXXdyLQP+8Oz3ZnUpw5inDIzLpRbUuAjI+IjUtguIK AkU1rZNdCXMOqEwCaomRitwaiX9H7yiDTKCUaqx8yAuAQWactWDdyFii2FA7IwVlD/GBqMWV weZsMfeWgPumKB3jyElm1RpkzULrtKbu7MToMH2fmWqBtTkRptABkY7VEd8qENKJBZKJGisk Fk6ylp8VzZdwbAtEDDTGK00Vg4PZGiIGbQo8mBqbc63DY+MdyUEksTTu2gTcqZMm/unQUJA8 xB4JrTAyljo/peIt6lsQa4+/eVolfKL1t1C3DY8f4wMoqnZORagnWA2oHsLsYKvcnqzA0QtY IIb1S1YatV+MNMFf3HuN7xr/jWlfdt59quXiOHU3qxIzXJo/OfC3mwNW4zQWJkG233UOf6YE rmrSaTIBTIWF8CxGY9iXPaJGNYSUa6R/VJS09EWeZgRz9Gk3h5AyDrdo5RFN9HNwOj41o0cj eLDF69092Lg5p5isuOqsrlPi5imHKcDtrXS7LacUI6H0c8onWoH9LuW99WznEtFgPJg++TAv f9M2x57Gzl+/nYTB5/Kpl1qdPPC91zUipiKbnF5f8bQpol0WC+ovmQARAQABiQIfBBgBAgAJ BQJTYPdaAhsMAAoJEESRkPMjWr074+0P/iEcN27dx3oBTzoeGEBhZUVQRZ7w4A61H/vW8oO8 IPkZv9kFr5pCfIonmHEbBlg6yfjeHXwF5SF2ywWRKkRsFHpaFWywxqk9HWXu8cGR1pFsrwC3 EdossuVbEFNmhjHvcAo11nJ7JFzPTEnlPjE6OY9tEDwl+kp1WvyXqNk9bosaX8ivikhmhB47 7BA3Kv8uUE7UL6p7CBdqumaOFISi1we5PYE4P/6YcyhQ9Z2wH6ad2PpwAFNBwxSu+xCrVmaD skAwknf6UVPN3bt67sFAaVgotepx6SPhBuH4OSOxVHMDDLMu7W7pJjnSKzMcAyXmdjON05Sz SaILwfceByvHAnvcFh2pXK9U4E/SyWZDJEcGRRt79akzZxls52stJK/2Tsr0vKtZVAwogiaK uSp+m6BRQcVVhTo/Kq3E0tSnsTHFeIO6QFHKJCJv4FRE3Dmtz15lueihUBowsq9Hk+u3UiLo SmrMAZ6KgA4SQxB2p8/M53kNJl92HHc9nc//aCQDi1R71NyhtSx+6PyivoBkuaKYs+S4pHmt sFE+5+pkUNROtm4ExLen4N4OL6Kq85mWGf2f6hd+OWtn8we1mADjDtdnDHuv+3E3cacFJPP/ wFV94ZhqvW4QcyBWcRNFA5roa7vcnu/MsCcBoheR0UdYsOnJoEpSZswvC/BGqJTkA2sf Message-ID: Date: Wed, 8 Apr 2020 10:24:02 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="------------897065045C309DDC7B5A9A95" Content-Language: en-US X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 192.134.164.83 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" This is a multi-part message in MIME format. --------------897065045C309DDC7B5A9A95 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit When the program name is very long, qemu-user may truncate it in /proc/self/stat. However the truncation must keep the ending ") " to conform to the proc manpage which says: (2) comm %s The filename of the executable, in parentheses. This is visible whether or not the executable is swapped out. To reproduce: $ ln -s /bin/cat $ qemu-x86_64 ./ /proc/self/stat Before the patch, you get: 1134631 (0 0 0 0 0 0 0 0 ... After the patch: 1134631 () 0 0 0 0 0 0 0 0 ... This fixes an issue with hwloc failing to parse /proc/self/stat when Ludovic Courtes was testing it in Guix over qemu-aarch64. Signed-off-by: Philippe_Mathieu-Daudé Signed-off-by: Brice Goglin diff --git a/linux-user/syscall.c b/linux-user/syscall.c --- a/linux-user/syscall.c +++ b/linux-user/syscall.c @@ -7305,7 +7305,11 @@ static int open_self_stat(void *cpu_env, int fd)          snprintf(buf, sizeof(buf), "%"PRId64 " ", val);        } else if (i == 1) {          /* app name */ -        snprintf(buf, sizeof(buf), "(%s) ", ts->bprm->argv[0]); +        char *ptr = buf; + +        *ptr++ = '('; +        ptr = stpncpy(ptr, ts->bprm->argv[0], sizeof(buf) - 3); +        strcpy(ptr, ") ");        } else if (i == 27) {          /* stack bottom */          val = start_stack; --------------897065045C309DDC7B5A9A95 Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: 8bit 
When the program name is very long, qemu-user may truncate it in
/proc/self/stat. However the truncation must keep the ending ") "
to conform to the proc manpage which says:
    (2) comm  %s
           The  filename of the executable, in parentheses.  This
           is visible whether or not the  executable  is  swapped
           out.

To reproduce:
$ ln -s /bin/cat <filenamewithmorethan128chars>
$ qemu-x86_64 ./<filenamewithmorethan128chars> /proc/self/stat

Before the patch, you get:
1134631 (<filenametruncated>0 0 0 0 0 0 0 0 ...
After the patch:
1134631 (<filenametruncat>) 0 0 0 0 0 0 0 0 ...

This fixes an issue with hwloc failing to parse /proc/self/stat
when Ludovic Courtes was testing it in Guix over qemu-aarch64.

Signed-off-by: Philippe_Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Brice Goglin <Brice.Goglin@inria.fr>

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -7305,7 +7305,11 @@ static int open_self_stat(void *cpu_env, int fd)
         snprintf(buf, sizeof(buf), "%"PRId64 " ", val);
       } else if (i == 1) {
         /* app name */
-        snprintf(buf, sizeof(buf), "(%s) ", ts->bprm->argv[0]);
+        char *ptr = buf;
+
+        *ptr++ = '(';
+        ptr = stpncpy(ptr, ts->bprm->argv[0], sizeof(buf) - 3);
+        strcpy(ptr, ") ");
       } else if (i == 27) {
         /* stack bottom */
         val = start_stack;
--------------897065045C309DDC7B5A9A95--