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Raise the warning level to -Wall -Wextra and resolve the warnings #609

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Raise the warning level to -Wall -Wextra and resolve the warnings #609

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a539422
Resolve the warnings reported at -Wall -Wextra
matejk Aug 17, 2026
80f7b6a
build: raise the warning level to -Wall -Wextra
matejk Aug 17, 2026
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4 changes: 2 additions & 2 deletions configure.ac
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Original file line number Diff line number Diff line change
Expand Up @@ -469,7 +469,7 @@ dnl Update flags
dnl Sets CFLAGS to force optimization and debugging options, which isn't quite kosher
dnl
AM_CPPFLAGS="-D_GNU_SOURCE -I\$(top_srcdir)/src -DLTFS_CONFIG_FILE='\"${sysconfdir}/ltfs.conf\"' -DLTFS_BASE_DIR='\"${prefix}\"'"
AM_CFLAGS="-Wall -Wsign-compare -fsigned-char ${FUSE_MODULE_CFLAGS} ${UUID_MODULE_CFLAGS} ${LIBXML2_MODULE_CFLAGS} ${ICU_MODULE_CFLAGS} ${SNMP_ENABLE} ${SNMP_MODULE_CFLAGS}"
AM_CFLAGS="${AM_CFLAGS} -Wall -Wextra -Wno-unused-parameter -Wno-missing-field-initializers -Wsign-compare -fsigned-char ${FUSE_MODULE_CFLAGS} ${UUID_MODULE_CFLAGS} ${LIBXML2_MODULE_CFLAGS} ${ICU_MODULE_CFLAGS} ${SNMP_ENABLE} ${SNMP_MODULE_CFLAGS}"

if test "x$use_fast" = "xyes"
then
Expand Down Expand Up @@ -529,7 +529,7 @@ then
SSE42=yes
fi

if test ${GCC_VERSION_MAJOR} -ge 8 -a ${GCC_VERSION_MINOR} -ge 0 -a "x$warning_as_error" = "xyes"
if test ${GCC_VERSION_MAJOR} -ge 8
then
AM_CFLAGS="${AM_CFLAGS} -Wno-stringop-truncation"
fi
Expand Down
4 changes: 2 additions & 2 deletions src/libltfs/arch/arch_info.c
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Expand Up @@ -72,7 +72,7 @@ void show_runtime_system_info(void)
ltfsmsg(LTFS_WARN, 17086W);
} else {
memset(kernel_version, 0, sizeof(kernel_version));
read(fd, kernel_version, sizeof(kernel_version));
(void)!read(fd, kernel_version, sizeof(kernel_version) - 1);
if((tmp = strchr(kernel_version, '\n')) != NULL)
*tmp = '\0';

Expand Down Expand Up @@ -118,7 +118,7 @@ void show_runtime_system_info(void)
} else {
if (fstat(fd, &stat_rel) != -1 && S_ISREG(stat_rel.st_mode)) {
memset(destribution, 0, sizeof(destribution));
read(fd, destribution, sizeof(destribution));
(void)!read(fd, destribution, sizeof(destribution) - 1);
if((tmp = strchr(destribution, '\n')) != NULL)
*tmp = '\0';
ltfsmsg(LTFS_INFO, 17089I, destribution);
Expand Down
12 changes: 7 additions & 5 deletions src/libltfs/fs.c
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Expand Up @@ -426,7 +426,9 @@ uint64_t fs_allocate_uid(struct ltfs_index *idx)
int fs_dentry_lookup(struct dentry *dentry, char **name)
{
char **dentry_names = NULL, *tmp_name = NULL;
int i, names, namelen = 0, ret = 0;
int ret = 0;
ssize_t i;
size_t names, namelen = 0;
Comment on lines +429 to +431

@XV02 XV02 Aug 18, 2026

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What warning was this fixing when compiling before? Can you please share details about the warning and specific platform? Thanks

@matejk matejk Aug 19, 2026 •
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Many warnings appear only with a higher -O level. This one is -Walloc-size-larger-than, reported by gcc 15 (Ubuntu 25.10 and 26.04) with --enable-fast (-O2); clang does not report it.

namelen + names is int, and gcc's range analysis finds it can be negative; converted to calloc's size_t argument that becomes ~2^64. Fixed by making names/namelen size_t.

struct dentry *d, *parent;
const char *lookup_name;

Expand All @@ -447,7 +449,7 @@ int fs_dentry_lookup(struct dentry *dentry, char **name)

d = dentry;
parent = d->parent;
for (i=names-1; i>=0; --i) {
for (i = (ssize_t)names - 1; i >= 0; --i) {
if (parent)
acquireread_mrsw(&parent->contents_lock);

Expand Down Expand Up @@ -483,9 +485,9 @@ int fs_dentry_lookup(struct dentry *dentry, char **name)
goto out;
}

for (namelen=0, i=0; i<names; ++i) {
for (namelen=0, i=0; i < (ssize_t)names; ++i) {
arch_strcat(tmp_name,tmp_len, dentry_names[i]);
if (i > 0 && i < names-1)
if (i > 0 && i < (ssize_t)names-1)
arch_strcat(tmp_name, tmp_len, "/");
}

Expand All @@ -496,7 +498,7 @@ int fs_dentry_lookup(struct dentry *dentry, char **name)
if (ret != 0 && tmp_name)
free(tmp_name);
if (dentry_names) { /* BEAM: constant condition - dentry_names has always non-zero value here. */
while (--names >= 0)
while (names-- > 0)
if (dentry_names[names])
free(dentry_names[names]);
free(dentry_names);
Expand Down
2 changes: 1 addition & 1 deletion src/libltfs/ltfs.c
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Expand Up @@ -4404,7 +4404,7 @@ void ltfs_enable_livelink_mode(struct ltfs_volume *vol)
*/
int ltfs_profiler_set(uint64_t source, struct ltfs_volume *vol)
{
int ret, ret_save = 0;
int ret = 0, ret_save = 0;

if (vol->iosched_handle) {
if (source & PROF_IOSCHED) {
Expand Down
3 changes: 2 additions & 1 deletion src/libltfs/ltfs_fsops.c
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Expand Up @@ -2000,7 +2000,8 @@ int ltfs_fsops_readlink_path(const char *path, char *buf, size_t size, ltfs_file

int ltfs_fsops_target_absolute_path(const char* link, const char* target, char* buf, size_t size )
{
char *work_buf, *target_buf, *temp_buf, *token, *next_token; /* work buffers for string */
char *work_buf, *target_buf, *token, *next_token; /* work buffers for string */
const char *temp_buf;
int len=0, len2=0; /* work variables for string length */

CHECK_ARG_NULL(link, -LTFS_NULL_ARG);
Expand Down
20 changes: 10 additions & 10 deletions src/libltfs/ltfstrace.c
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Expand Up @@ -694,37 +694,37 @@ int ltfs_trace_dump(char *fname, const char *work_dir)
trc_header->header_size + req_header->header_size + fn_trc_header->header_size;

/* Write headers */
(void)arch_write(fd, trc_header, sizeof(struct trace_header));
(void)arch_write(fd, req_header, sizeof(struct request_header));
(void)!arch_write(fd, trc_header, sizeof(struct trace_header));
(void)!arch_write(fd, req_header, sizeof(struct request_header));

/* Write request trace data */
ltfs_mutex_lock(&req_trace->req_trace_lock);
(void)arch_write(fd, req_trace->entries, REQ_TRACE_SIZE);
(void)!arch_write(fd, req_trace->entries, REQ_TRACE_SIZE);
ltfs_mutex_unlock(&req_trace->req_trace_lock);

/* Write function trace header */
(void)arch_write(fd, &fn_trc_header->header_size, sizeof(uint32_t));
(void)arch_write(fd, &fn_trc_header->num_of_fn_trace, sizeof(uint32_t));
(void)!arch_write(fd, &fn_trc_header->header_size, sizeof(uint32_t));
(void)!arch_write(fd, &fn_trc_header->num_of_fn_trace, sizeof(uint32_t));
for (unsigned int i=0; i<n; i++)
(void)arch_write(fd, &fn_trc_header->req_t_desc[i], sizeof(struct function_trace_descriptor));
(void)arch_write(fd, &fn_trc_header->crc, sizeof(uint32_t));
(void)!arch_write(fd, &fn_trc_header->req_t_desc[i], sizeof(struct function_trace_descriptor));
(void)!arch_write(fd, &fn_trc_header->crc, sizeof(uint32_t));
free(fn_trc_header->req_t_desc);
fn_trc_header->req_t_desc = NULL;

/* Write function trace data */
for (fsitem=fs_tr_list; fsitem != NULL; fsitem=fsitem->hh.next) {
acquireread_mrsw(&fsitem->fn_entry->trace_lock);
(void)arch_write(fd, fsitem->fn_entry->entries, FS_FN_TRACE_SIZE);
(void)!arch_write(fd, fsitem->fn_entry->entries, FS_FN_TRACE_SIZE);

@XV02 XV02 Aug 18, 2026

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I have a little comment on these changes, I suggested this for an idiomatic approach of GCC shenanigans to suppress a warning, but making some tests I see no warnings with the original way this was done, do you have more info about the specific warnings and system you saw a warning being raised?

@matejk matejk Aug 19, 2026

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The warning is -Wunused-result on write(): glibc marks it warn_unused_result only when _FORTIFY_SOURCE is set, and configure sets -D_FORTIFY_SOURCE=2 only with --enable-fast (-O2). The default ./configure builds with -O0 -D_FORTIFY_SOURCE=0, where nothing is reported — most likely the difference.

Reproduced with --enable-fast on gcc 15.2 (Ubuntu 25.10 and 26.04): 9 warnings at ltfstrace.c:697–722. A plain (void) cast does not silence it on gcc; (void)! does. clang does not report these.

Should this be commented at the call sites for future readers?

releaseread_mrsw(&fsitem->fn_entry->trace_lock);
}
for (admitem=admin_tr_list; admitem != NULL; admitem=admitem->hh.next) {
acquireread_mrsw(&admitem->fn_entry->trace_lock);
(void)arch_write(fd, admitem->fn_entry->entries, ADMIN_FN_TRACE_SIZE);
(void)!arch_write(fd, admitem->fn_entry->entries, ADMIN_FN_TRACE_SIZE);
releaseread_mrsw(&admitem->fn_entry->trace_lock);
}
TAILQ_FOREACH (tailq_item, acomp, list) {
acquireread_mrsw(&tailq_item->fn_entry->trace_lock);
(void)arch_write(fd, tailq_item->fn_entry->entries, ADMIN_FN_TRACE_SIZE);
(void)!arch_write(fd, tailq_item->fn_entry->entries, ADMIN_FN_TRACE_SIZE);
releaseread_mrsw(&tailq_item->fn_entry->trace_lock);
}
}
Expand Down
2 changes: 1 addition & 1 deletion src/libltfs/tape.c
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Expand Up @@ -2978,7 +2978,7 @@ void parse_vol(char *str, int start_len, int end_len)
*/
int u_get_truncate_size(const char *name, int name_len, int max_size)
{
int32_t size = 0, re_size;
int32_t size = 0, re_size = 0;
UChar32 c;
UErrorCode err = U_ZERO_ERROR;

Expand Down
5 changes: 3 additions & 2 deletions src/libltfs/xml_writer_libltfs.c
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Expand Up @@ -882,8 +882,9 @@ int xml_schema_to_tape(char *reason, struct ltfs_volume *vol)
}

/* Generate the Index. */
asprintf(&creator, "%s - %s", vol->creator, reason);
if (creator) {
if (asprintf(&creator, "%s - %s", vol->creator, reason) < 0)
creator = NULL;
if (creator != NULL) {
ret = _xml_write_schema(writer, creator, vol->index);
if (ret < 0) {
ltfsmsg(LTFS_ERR, 17055E, ret);
Expand Down
5 changes: 4 additions & 1 deletion src/tape_drivers/generic/itdtimg/itdtimg_tc.c
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Expand Up @@ -947,7 +947,10 @@ int itdtimage_read_attribute(void *vstate, const tape_partition_t part, const ui
return -EDEV_HARDWARE_ERROR;
}

fread(buf, 1, data2ReadFromFile, state->img_file);
if (fread(buf, 1, data2ReadFromFile, state->img_file) != data2ReadFromFile) {
ltfsmsg(LTFS_ERR, 31002E, (long long)attrLength, state->filename, offset);
return -EDEV_HARDWARE_ERROR;
}
return DEVICE_GOOD;
}

Expand Down
12 changes: 8 additions & 4 deletions src/tape_drivers/linux/sg/sg_scsi_tape.c
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Expand Up @@ -449,6 +449,7 @@ static int _inquiry_low(struct sg_tape *device, uint8_t page, unsigned char *buf
int sg_get_drive_identifier(struct sg_tape *device, scsi_device_identifier *id_data)
{
int ret;
size_t serial_len;
unsigned char inquiry_buf[MAX_INQ_LEN];

CHECK_ARG_NULL(id_data, -LTFS_NULL_ARG);
Expand All @@ -466,17 +467,20 @@ int sg_get_drive_identifier(struct sg_tape *device, scsi_device_identifier *id_d
return -EDEV_DEVICE_UNSUPPORTABLE;
}

strncpy(id_data->vendor_id, (char*)(&(inquiry_buf[8])), VENDOR_ID_LENGTH);
strncpy(id_data->product_id, (char*)(&(inquiry_buf[16])), PRODUCT_ID_LENGTH);
strncpy(id_data->product_rev, (char*)(&(inquiry_buf[32])), PRODUCT_REV_LENGTH);
memcpy(id_data->vendor_id, &inquiry_buf[8], VENDOR_ID_LENGTH);
memcpy(id_data->product_id, &inquiry_buf[16], PRODUCT_ID_LENGTH);
memcpy(id_data->product_rev, &inquiry_buf[32], PRODUCT_REV_LENGTH);

ret = _inquiry_low(device, 0x80, inquiry_buf, MAX_INQ_LEN);
if( ret < 0 ) {
ltfsmsg(LTFS_INFO, 30206I, ret);
return ret;
}

strncpy(id_data->unit_serial, (char*)(&(inquiry_buf[4])), inquiry_buf[3]);
serial_len = inquiry_buf[3];
if (serial_len > UNIT_SERIAL_LENGTH)
serial_len = UNIT_SERIAL_LENGTH;
memcpy(id_data->unit_serial, &inquiry_buf[4], serial_len);

return 0;
}
45 changes: 22 additions & 23 deletions src/tape_drivers/linux/sg/sg_tape.c
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Expand Up @@ -288,7 +288,7 @@ static int _get_dump(struct sg_data *priv, char *fname)
long long data_length, buf_offset;
int dumpfd = -1;
int transfer_size, num_transfers, excess_transfer;
int i, bytes;
int bytes;
unsigned char cap_buf[DUMP_HEADER_SIZE];
unsigned char *dump_buf;
int buf_id;
Expand Down Expand Up @@ -334,14 +334,11 @@ static int _get_dump(struct sg_data *priv, char *fname)

/* start to transfer data */
buf_offset = 0;
i = 0;
ltfsmsg(LTFS_DEBUG, 30257D);
while(num_transfers)
{
int length;

i++;

/* Allocation Length is transfer_size or excess_transfer*/
if(excess_transfer && num_transfers == 1)
length = excess_transfer;
Expand Down Expand Up @@ -531,8 +528,10 @@ static int _raw_open(struct sg_data *priv)
priv->dev.fd = -1;
return -EDEV_DEVICE_UNOPENABLE; /* Unexpected device is opened */
}
} else
strncpy(priv->drive_serial, id_data.unit_serial, sizeof(priv->drive_serial) - 1);
} else {
snprintf(priv->drive_serial, sizeof(priv->drive_serial), "%.*s",
(int)sizeof(priv->drive_serial) - 1, id_data.unit_serial);
}

/* Get SCSI ID */
if (! ioctl(priv->dev.fd, SG_GET_SCSI_ID, &scsi_id)) {
Expand All @@ -550,12 +549,12 @@ static int _raw_open(struct sg_data *priv)
ltfsmsg(LTFS_INFO, 30214I, id_data.product_rev);
ltfsmsg(LTFS_INFO, 30215I, priv->drive_serial);

strncpy(priv->info.name, priv->devname, TAPE_DEVNAME_LEN_MAX + 1);
strncpy(priv->info.vendor, id_data.vendor_id, TAPE_VENDOR_NAME_LEN_MAX + 1);
strncpy(priv->info.model, id_data.product_id, TAPE_MODEL_NAME_LEN_MAX + 1);
strncpy(priv->info.serial_number, id_data.unit_serial, TAPE_SERIAL_LEN_MAX + 1);
strncpy(priv->info.product_rev, id_data.product_rev, PRODUCT_REV_LENGTH + 1);
strncpy(priv->info.product_name, _generate_product_name(id_data.product_id), PRODUCT_NAME_LENGTH + 1);
snprintf(priv->info.name, sizeof(priv->info.name), "%.*s", (int)sizeof(priv->info.name) - 1, priv->devname);
snprintf(priv->info.vendor, sizeof(priv->info.vendor), "%.*s", (int)sizeof(priv->info.vendor) - 1, id_data.vendor_id);
snprintf(priv->info.model, sizeof(priv->info.model), "%.*s", (int)sizeof(priv->info.model) - 1, id_data.product_id);
snprintf(priv->info.serial_number, sizeof(priv->info.serial_number), "%.*s", (int)sizeof(priv->info.serial_number) - 1, id_data.unit_serial);
snprintf(priv->info.product_rev, sizeof(priv->info.product_rev), "%.*s", (int)sizeof(priv->info.product_rev) - 1, id_data.product_rev);
snprintf(priv->info.product_name, sizeof(priv->info.product_name), "%.*s", (int)sizeof(priv->info.product_name) - 1, _generate_product_name(id_data.product_id));

return 0;
}
Expand Down Expand Up @@ -1646,9 +1645,9 @@ int sg_inquiry(void *device, struct tc_inq *inq)
return ret;

memset(inq, 0, sizeof(struct tc_inq));
strncpy((char*)inq->vid, (char*)inq_page.data + 8, VENDOR_ID_LENGTH);
strncpy((char*)inq->pid, (char*)inq_page.data + 16, PRODUCT_ID_LENGTH);
strncpy((char*)inq->revision, (char*)inq_page.data + 32, PRODUCT_REV_LENGTH);
memcpy(inq->vid, inq_page.data + 8, VENDOR_ID_LENGTH);
memcpy(inq->pid, inq_page.data + 16, PRODUCT_ID_LENGTH);
memcpy(inq->revision, inq_page.data + 32, PRODUCT_REV_LENGTH);

inq->devicetype = priv->drive_type;

Expand All @@ -1657,7 +1656,7 @@ int sg_inquiry(void *device, struct tc_inq *inq)
else
vendor_length = 20;

strncpy((char*)inq->vendor, (char*)inq_page.data + 36, vendor_length);
memcpy(inq->vendor, inq_page.data + 36, vendor_length);
inq->vendor[vendor_length] = '\0';

return ret;
Expand Down Expand Up @@ -1710,7 +1709,7 @@ int sg_test_unit_ready(void *device)
case -EDEV_NEED_INITIALIZE:
case -EDEV_CONFIGURE_CHANGED:
print_msg = false;
/* fall throuh */
/* fall through */
case -EDEV_NO_MEDIUM:
case -EDEV_BECOMING_READY:
case -EDEV_MEDIUM_MAY_BE_CHANGED:
Expand Down Expand Up @@ -4432,12 +4431,12 @@ int sg_get_device_list(struct tc_drive_info *buf, int count)
}

if (found < count && buf) {
strncpy(buf[found].name, devname, TAPE_DEVNAME_LEN_MAX + 1);
strncpy(buf[found].vendor, identifier.vendor_id, TAPE_VENDOR_NAME_LEN_MAX + 1);
strncpy(buf[found].model, identifier.product_id, TAPE_MODEL_NAME_LEN_MAX + 1);
strncpy(buf[found].serial_number, identifier.unit_serial, TAPE_SERIAL_LEN_MAX + 1);
strncpy(buf[found].product_rev, identifier.product_rev, PRODUCT_REV_LENGTH + 1);
strncpy(buf[found].product_name, _generate_product_name(identifier.product_id), PRODUCT_NAME_LENGTH + 1);
snprintf(buf[found].name, sizeof(buf[found].name), "%.*s", (int)sizeof(buf[found].name) - 1, devname);
snprintf(buf[found].vendor, sizeof(buf[found].vendor), "%.*s", (int)sizeof(buf[found].vendor) - 1, identifier.vendor_id);
snprintf(buf[found].model, sizeof(buf[found].model), "%.*s", (int)sizeof(buf[found].model) - 1, identifier.product_id);
snprintf(buf[found].serial_number, sizeof(buf[found].serial_number), "%.*s", (int)sizeof(buf[found].serial_number) - 1, identifier.unit_serial);
snprintf(buf[found].product_rev, sizeof(buf[found].product_rev), "%.*s", (int)sizeof(buf[found].product_rev) - 1, identifier.product_rev);
snprintf(buf[found].product_name, sizeof(buf[found].product_name), "%.*s", (int)sizeof(buf[found].product_name) - 1, _generate_product_name(identifier.product_id));

if (! ioctl(dev.fd, SG_GET_SCSI_ID, &scsi_id)) {
buf[found].host = scsi_id.host_no;
Expand Down
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