Bug Summary

File:daq/dqm/src/DqmSharedMem.cc
Warning:line 35, column 36
The parameter must not be null

Annotated Source Code

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clang -cc1 -cc1 -triple x86_64-unknown-linux-gnu -O3 -analyze -disable-free -clear-ast-before-backend -disable-llvm-verifier -discard-value-names -main-file-name DqmSharedMem.cc -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -setup-static-analyzer -mrelocation-model pic -pic-level 2 -fhalf-no-semantic-interposition -mframe-pointer=none -fmath-errno -ffp-contract=on -fno-rounding-math -mconstructor-aliases -funwind-tables=2 -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -fdebug-compilation-dir=/data/b2soft/buildbot/development/build -fcoverage-compilation-dir=/data/b2soft/buildbot/development/build -resource-dir /cvmfs/belle.cern.ch/el9/externals/v02-04-00/Linux_x86_64/common/lib/clang/21 -isystem /cvmfs/belle.cern.ch/el9/externals/v02-04-00/Linux_x86_64/common/include/c++ -isystem /cvmfs/belle.cern.ch/el9/externals/v02-04-00/Linux_x86_64/common/include/c++/x86_64-redhat-linux -isystem /cvmfs/belle.cern.ch/el9/externals/v02-04-00/Linux_x86_64/common/include/c++/backward -isystem /cvmfs/belle.cern.ch/el9/externals/v02-04-00/include -isystem /cvmfs/belle.cern.ch/el9/externals/v02-04-00/Linux_x86_64/common/include/python3.12 -isystem /cvmfs/belle.cern.ch/el9/externals/v02-04-00/include/CLHEP -isystem /cvmfs/belle.cern.ch/el9/externals/v02-04-00/Linux_x86_64/common/include/Geant4 -isystem /cvmfs/belle.cern.ch/el9/externals/v02-04-00/Linux_x86_64/common/include -isystem /cvmfs/belle.cern.ch/el9/externals/v02-04-00/include/root -isystem /cvmfs/belle.cern.ch/el9/externals/v02-04-00/include/belle_legacy -I include/ -D _PACKAGE_="daq" -D G4UI_USE_TCSH -D RaveDllExport= -D HAS_SQLITE -D HAS_CALLGRIND -I include -I /cvmfs/belle.cern.ch/el9/externals/v02-04-00/Linux_x86_64/common/include/libxml2 -internal-isystem /cvmfs/belle.cern.ch/el9/externals/v02-04-00/Linux_x86_64/common/bin/../lib64/gcc/x86_64-redhat-linux/15.2.0/../../../../include/c++ -internal-isystem /cvmfs/belle.cern.ch/el9/externals/v02-04-00/Linux_x86_64/common/bin/../lib64/gcc/x86_64-redhat-linux/15.2.0/../../../../include/c++/x86_64-redhat-linux -internal-isystem /cvmfs/belle.cern.ch/el9/externals/v02-04-00/Linux_x86_64/common/bin/../lib64/gcc/x86_64-redhat-linux/15.2.0/../../../../include/c++/backward -internal-isystem /cvmfs/belle.cern.ch/el9/externals/v02-04-00/Linux_x86_64/common/lib/clang/21/include -internal-isystem /usr/local/include -internal-isystem /cvmfs/belle.cern.ch/el9/externals/v02-04-00/Linux_x86_64/common/bin/../lib64/gcc/x86_64-redhat-linux/15.2.0/../../../../x86_64-redhat-linux/include -internal-externc-isystem /include -internal-externc-isystem /usr/include -Wno-missing-braces -Wno-unused-command-line-argument -std=c++20 -fdeprecated-macro -ferror-limit 19 -fgnuc-version=4.2.1 -fno-implicit-modules -fskip-odr-check-in-gmf -fcxx-exceptions -fexceptions -vectorize-loops -vectorize-slp -analyzer-output=html -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /scan_build/2026-05-31-004316-385593-1 -x c++ daq/dqm/src/DqmSharedMem.cc
1/**************************************************************************
2 * basf2 (Belle II Analysis Software Framework) *
3 * Author: The Belle II Collaboration *
4 * *
5 * See git log for contributors and copyright holders. *
6 * This file is licensed under LGPL-3.0, see LICENSE.md. *
7 **************************************************************************/
8
9#include "daq/dqm/DqmSharedMem.h"
10
11#include <fcntl.h>
12#include <sys/ipc.h>
13#include <sys/sem.h>
14#include <sys/shm.h>
15#include <sys/types.h>
16#include <unistd.h>
17
18#include <cstring>
19
20using namespace Belle2;
21using namespace std;
22
23// Constructor / Destructor
24
25DqmSharedMem::DqmSharedMem(const char* name, int size, bool writeable, const char* user)
26{
27 bool hasFile = false;
28 std::string tmpPathName;
29 // 0. Determine shared memory type
30 if (strcmp(name, "private") != 0) { // Global
1
Assuming the condition is true
→
2
←
Taking true branch
→
31 hasFile = true;
32 if (user) {
3
←
Assuming 'user' is null
→
4
←
Taking false branch
→
33 tmpPathName = getTmpFileName(user, name);
34 } else {
35 tmpPathName = getTmpFileName(getenv("USER"), name);
5
←
The parameter must not be null
36 }
37 printf("Open Shared Memory: %s writeable %d\n", tmpPathName.c_str(), writeable);
38 int tmpFilefd = open(tmpPathName.c_str(), O_CREAT0100 | O_EXCL0200 | O_RDWR02, 0644);
39 // existance of file does not really imply shared mem is existing.
40 // -> better we do not rely and update the content anyway!
41 if (tmpFilefd > 0) { // a new shared memory file created
42 printf("DqmSharedMem: Creating a new tmp file %s\n", name);
43 m_new = true;
44 close(tmpFilefd); // will open again later
45 } else if (tmpFilefd == -1 && errno(*__errno_location ()) == EEXIST17) { // shm already there
46 printf("DqmSharedMem: Updating existing tmp file %s\n", name);
47 m_new = false;
48 } else {
49 printf("DqmSharedMem: error to open tmp file %s\n", tmpPathName.c_str());
50 return;
51 }
52 m_shmkey = ftok(tmpPathName.c_str(), 1);
53 m_semkey = ftok(tmpPathName.c_str(), 2);
54 } else { // Private
55 hasFile = false;
56 m_new = true;
57 m_shmkey = IPC_PRIVATE((__key_t) 0);
58 m_semkey = IPC_PRIVATE((__key_t) 0);
59 printf("DqmSharedMem: Opening private shared memory\n");
60 }
61
62 printf("Shared memory/Semaphore Keys: $%X $%X\n", m_shmkey, m_semkey);
63 // Behavior:
64 // - IPC_CREATE will open existing or create new one
65 // - IPC_CREATE|IPC_EXCL will create new one and fail is existing
66 // - 0 will open existing one and fails if not existing
67
68 // 1. Open shared memory
69 m_shmid = shmget(m_shmkey, size * 4, IPC_CREAT01000 | IPC_EXCL02000 | 0644);
70 if (m_shmid >= 0) {
71 printf("Created new shm %d for key $%X\n", m_shmid, m_shmkey);
72 } else if (errno(*__errno_location ()) == EEXIST17) {
73 m_shmid = shmget(m_shmkey, 0, 0);
74 printf("Found existing shm %d for key $%X\n", m_shmid, m_shmkey);
75 }
76 if (m_shmid < 0) {
77 perror("SharedMem::shmget");
78 return;
79 }
80 if (!writeable) {
81 printf("ShM ID %d opened Readonly\n", m_shmid);
82 m_shmadr = (int*) shmat(m_shmid, 0, SHM_RDONLY010000);
83 } else {
84 printf("ShM ID %d opened Writeable\n", m_shmid);
85 m_shmadr = (int*) shmat(m_shmid, 0, 0);
86 }
87 if (m_shmadr == (int*) - 1) {
88 perror("DqmSharedMem::shmat");
89 return;
90 }
91
92 // 2. Open semaphore
93
94 // Behavior:
95 // - IPC_CREATE will open existing or create new one
96 // - IPC_CREATE|IPC_EXCL will create new one and fail is existing
97 // - 0 will open existing one and fails if not existing
98 m_semid = semget(m_semkey, 1, IPC_CREAT01000 | IPC_EXCL02000 | 0666);
99 if (m_semid >= 0) {
100 // POSIX doesn't guarantee any particular state of our fresh semaphore
101 int semval = 1; //unlocked state
102 printf("Semaphore ID %d created for key $%X\n", m_semid, m_semkey);
103 if (semctl(m_semid, 0, SETVAL16, semval) == -1) { //set 0th semaphore to semval
104 perror("Initializing semaphore with semctl() failed.");
105 return;
106 }
107 } else if (errno(*__errno_location ()) == EEXIST17) {
108 m_semid = semget(m_semkey, 1, 0); // obtain existing one
109 printf("Found existing Semaphore ID %d for key $%X\n", m_semid, m_semkey);
110 }
111 if (m_semid < 0) {
112 perror("DqmSharedMem::shmget");
113 return;
114 }
115
116 // 3. Put id of shm and semaphore in tmp file
117 if (hasFile) {
118 // private shm dont have a file, thus need to skip
119 bool updateneeded = m_new;
120 // 3.1 check if id of shm and semaphore in tmp file need update
121 if (!m_new) {
122 int shmid = 0, semid = 0;
123 if (getIdFromTmpFileName(tmpPathName.c_str(), shmid, semid)) {
124 updateneeded = (shmid != m_shmid || semid != m_semid);
125 printf("tmp file %s content still uptodate\n", tmpPathName.c_str());
126 } else {
127 updateneeded = true; // could not open file or empty
128 }
129 }
130 // 3.2 put id of shm and semaphore in tmp file
131 if (updateneeded) {
132 char shminfo[256];
133 int tmpFilefd = open(tmpPathName.c_str(), O_RDWR02, 0644);
134 if (tmpFilefd < 0) {
135 printf("SharedMem: error to reopen tmp file %s\n", tmpPathName.c_str());
136 return;
137 }
138 snprintf(shminfo, sizeof(shminfo), "%d %d\n", m_shmid, m_semid);
139 int is = write(tmpFilefd, shminfo, strlen(shminfo));
140 if (is < 0) perror("write");
141 close(tmpFilefd);
142 printf("tmp file %s has been updated with shminfo \"%s\"\n", tmpPathName.c_str(), shminfo);
143 }
144 }
145 printf("DqmSharedMem: opened. shmid = %d, semid = %d\n", m_shmid, m_semid);
146}
147
148DqmSharedMem::DqmSharedMem(int shm_id, int sem_id)
149{
150 // Open DqmSharedMemory with given IDs, this is only possible for read-only access
151 m_shmid = shm_id;
152 m_shmadr = (int*) shmat(m_shmid, 0, SHM_RDONLY010000);
153 if (m_shmadr == (int*) - 1) {
154 perror("DqmSharedMem::shmat");
155 return;
156 }
157 m_semid = sem_id;
158 printf("DqmSharedMem: open shmid = %d, semid = %d\n", m_shmid, m_semid);
159}
160
161DqmSharedMem::~DqmSharedMem(void)
162{
163 /// this killed the shared mems if the b2hlt... utils are run, thus commented!
164
165 //shmdt((const void*) m_shmadr);
166 //shmctl(m_shmid, IPC_RMID, NULL);
167 //printf("DqmSharedMem: destructor called for ID %d\n", m_shmid);
168 // TODO: problem, neither semaphore nor tmp file are deleted if they exist
169 // TODO: there is no guarantee that the destructor is called (e.g. on exit(), crash)
170 // printf("DqmSharedMem: destructor called for %s\n", m_strbuf);
171}
172
173void* DqmSharedMem::ptr(void)
174{
175 return (void*) m_shmadr;
176}
177
178int DqmSharedMem::shmid(void)
179{
180 return m_shmid;
181}
182
183bool DqmSharedMem::IsCreated(void)
184{
185 return m_new;
186}
187
188std::string DqmSharedMem::getTmpFileName(std::string user, std::string name)
189{
190 return string("/tmp/") + user + string("_SHM_") + name;
191}
192
193bool DqmSharedMem::getIdFromTmpFileName(std::string filename, int& shmid, int& semid)
194{
195 char shminfo[256];
196 int fd = open(filename.c_str(), O_RDONLY00);
197 if (fd < 0) {
198 printf("DqmSharedMem: error to reopen tmp file %s\n", filename.c_str());
199 return false;
200 }
201 shmid = -1;
202 semid = -1;
203 memset(shminfo, 0, sizeof(shminfo));
204 int n = read(fd, shminfo, sizeof(shminfo));
205 close(fd);
206 sscanf(shminfo, "%d %d", &shmid, &semid);
207 return (n >= 3 && shmid >= 0 && semid >= 0);
208}
209
210void DqmSharedMem::lock()
211{
212 struct sembuf sb;
213 sb.sem_num = 0;
214 sb.sem_op = -1;
215 sb.sem_flg = 0;
216 while (semop(m_semid, &sb, 1) == -1) {
217 if (errno(*__errno_location ()) == EINTR4) {
218 //interrupted by signal (e.g. window size changed), try again
219 continue;
220 } else {
221 perror("lock:semop");
222 exit(-1);
223 }
224 }
225}
226
227void DqmSharedMem::unlock()
228{
229 struct sembuf sb;
230 sb.sem_num = 0;
231 sb.sem_op = 1;
232 sb.sem_flg = 0;
233 while (semop(m_semid, &sb, 1) == -1) {
234 if (errno(*__errno_location ()) == EINTR4) {
235 //interrupted by signal (e.g. window size changed), try again
236 continue;
237 } else {
238 perror("unlock:semop");
239 exit(-1);
240 }
241 }
242}
243
244bool DqmSharedMem::isLocked()
245{
246 int ignored = 0;
247 return (semctl(m_semid, 0, GETVAL12, ignored) == 0); //0: locked, 1: unlocked
248}
249
250