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iiod: Restore support for reading/writing all attributes
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Libiio's new API does not allow reading or writing all attributes at the
same time. However, old clients connected to the old interface might
still try to use it.

Re-implement it in IIOD on top of the new API so that old clients still
work.

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
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@pcercuei
pcercuei committed Nov 27, 2023
1 parent 7d97827 commit c759f51
Showing 1 changed file with 177 additions and 12 deletions.
189 changes: 177 additions & 12 deletions iiod/ops.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1302,6 +1302,110 @@ ssize_t rw_dev(struct parser_pdata *pdata, struct iio_device *dev,
return ret;
}

static inline uint32_t iiod_htobe32(uint32_t word)
{
#if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
return word;
#elif defined(__GNUC__)
return __builtin_bswap32(word);
#else
return ((word & 0xff) << 24) | ((word & 0xff00) << 8) |
((word >> 8) & 0xff00) | ((word >> 24) & 0xff);
#endif
}

static inline uint32_t iiod_be32toh(uint32_t word)
{
return iiod_htobe32(word);
}

typedef struct iio_attr * (*rw_attr_cb_t)(const void *, unsigned int);

static int buffer_analyze(unsigned int nb, const char *src, size_t len)
{
while (nb--) {
int32_t val;

if (len < 4)
return -EINVAL;

val = (int32_t) iiod_be32toh(*(uint32_t *) src);
src += 4;
len -= 4;

if (val > 0) {
if ((uint32_t) val > len)
return -EINVAL;

/* Align the length to 4 bytes */
if (val & 3)
val = ((val >> 2) + 1) << 2;
len -= val;
src += val;
}
}

/* We should have analyzed the whole buffer by now */
return !len ? 0 : -EINVAL;
}

static ssize_t read_each_attr(const void *iio, char *buf, size_t len,
unsigned int nb, rw_attr_cb_t cb)
{
const struct iio_attr *attr;
unsigned int i;
char *ptr = buf;
ssize_t ret;

for (i = 0; len >= 4 && i < nb; i++) {
attr = (*cb)(iio, i);
if (!attr)
ret = -ENOENT;
else
ret = iio_attr_read_raw(attr, ptr + 4, len - 4);
*(uint32_t *)ptr = iiod_htobe32(ret);

/* Align the length to 4 bytes */
ret = ret < 0 ? 0 : (ret + 3) & ~0x3;
ptr += 4 + ret;
len -= 4 + ret;
}

return ptr - buf;
}

static ssize_t write_each_attr(const void *iio, const char *buf, size_t len,
unsigned int nb, rw_attr_cb_t cb)
{
const struct iio_attr *attr;
const char *ptr = buf;
unsigned int i;
ssize_t ret;
int32_t val;

ret = buffer_analyze(nb, buf, len);
if (ret < 0)
return ret;

for (i = 0; i < nb; i++) {
val = (int32_t) iiod_be32toh(*(uint32_t *)ptr);
ptr += 4;

if (val > 0) {
attr = (*cb)(iio, i);
if (!attr)
continue;

iio_attr_write_raw(attr, ptr, val);

/* Align the length to 4 bytes */
ptr += (val + 3) & ~0x3;
}
}

return ptr - buf;
}

ssize_t read_dev_attr(struct parser_pdata *pdata, struct iio_device *dev,
const char *name, enum iio_attr_type type)
{
Expand All @@ -1312,12 +1416,32 @@ ssize_t read_dev_attr(struct parser_pdata *pdata, struct iio_device *dev,
* of data. */
char buf[0x10000];
ssize_t ret = -EINVAL;
unsigned int nb;

if (!dev) {
print_value(pdata, -ENODEV);
return -ENODEV;
}

if (!name) {
switch (type) {
case IIO_ATTR_TYPE_DEVICE:
nb = iio_device_get_attrs_count(dev);
ret = read_each_attr(dev, buf, sizeof(buf) - 1, nb,
(rw_attr_cb_t)iio_device_get_attr);
break;
case IIO_ATTR_TYPE_DEBUG:
nb = iio_device_get_debug_attrs_count(dev);
ret = read_each_attr(dev, buf, sizeof(buf) - 1, nb,
(rw_attr_cb_t)iio_device_get_debug_attr);
break;
default:
return -EINVAL;
}

goto out_print_value;
}

switch (type) {
case IIO_ATTR_TYPE_DEVICE:
attr = iio_device_find_attr(dev, name);
Expand Down Expand Up @@ -1354,6 +1478,7 @@ ssize_t read_dev_attr(struct parser_pdata *pdata, struct iio_device *dev,
break;
}

out_print_value:
print_value(pdata, ret);
if (ret < 0)
return ret;
Expand All @@ -1367,21 +1492,41 @@ ssize_t write_dev_attr(struct parser_pdata *pdata, struct iio_device *dev,
{
const struct iio_device_pdata *dev_pdata;
const struct iio_attr *attr;
unsigned int nb;
ssize_t ret = -ENOMEM;
char *buf;

if (!dev) {
ret = -ENODEV;
goto err_print_value;
goto out_print_value;
}

buf = malloc(len);
if (!buf)
goto err_print_value;
goto out_print_value;

ret = read_all(pdata, buf, len);
if (ret < 0)
goto err_free_buffer;
goto out_free_buffer;

if (!name) {
switch (type) {
case IIO_ATTR_TYPE_DEVICE:
nb = iio_device_get_attrs_count(dev);
ret = write_each_attr(dev, buf, len - 1, nb,
(rw_attr_cb_t)iio_device_get_attr);
break;
case IIO_ATTR_TYPE_DEBUG:
nb = iio_device_get_debug_attrs_count(dev);
ret = write_each_attr(dev, buf, len - 1, nb,
(rw_attr_cb_t)iio_device_get_debug_attr);
break;
default:
return -EINVAL;
}

goto out_print_value;
}

switch (type) {
case IIO_ATTR_TYPE_DEVICE:
Expand Down Expand Up @@ -1419,30 +1564,42 @@ ssize_t write_dev_attr(struct parser_pdata *pdata, struct iio_device *dev,
break;
}

err_free_buffer:
out_free_buffer:
free(buf);
err_print_value:
out_print_value:
print_value(pdata, ret);
return ret;
}

ssize_t read_chn_attr(struct parser_pdata *pdata,
struct iio_channel *chn, const char *name)
{
char buf[1024];
/* We use a very large buffer here, as if attr is NULL all the
* attributes will be read, which may represents a few kilobytes worth
* of data. */
char buf[0x10000];
ssize_t ret = -ENODEV;
const struct iio_attr *attr;
unsigned int nb;

if (chn) {
if (!chn) {
ret = pdata->dev ? -ENXIO : -ENODEV;
goto out_print_value;
}

if (!name) {
nb = iio_channel_get_attrs_count(chn);
ret = read_each_attr(chn, buf, sizeof(buf) - 1, nb,
(rw_attr_cb_t)iio_channel_get_attr);
} else {
attr = iio_channel_find_attr(chn, name);
if (attr)
ret = iio_attr_read_raw(attr, buf, sizeof(buf) - 1);
else
ret = -ENOENT;
} else {
ret = pdata->dev ? -ENXIO : -ENODEV;
}

out_print_value:
print_value(pdata, ret);
if (ret < 0)
return ret;
Expand All @@ -1456,6 +1613,7 @@ ssize_t write_chn_attr(struct parser_pdata *pdata,
{
const struct iio_attr *attr;
ssize_t ret = -ENOMEM;
unsigned int nb;
char *buf;

buf = malloc(len);
Expand All @@ -1466,14 +1624,21 @@ ssize_t write_chn_attr(struct parser_pdata *pdata,
if (ret < 0)
goto err_free_buffer;

if (chn) {
if (!chn) {
ret = pdata->dev ? -ENXIO : -ENODEV;
goto err_free_buffer;
}

if (!name) {
nb = iio_channel_get_attrs_count(chn);
ret = write_each_attr(chn, buf, sizeof(buf) - 1, nb,
(rw_attr_cb_t)iio_channel_get_attr);
} else {
attr = iio_channel_find_attr(chn, name);
if (attr)
ret = iio_attr_write_raw(attr, buf, len);
else
ret = -ENOENT;
} else {
ret = pdata->dev ? -ENXIO : -ENODEV;
}

err_free_buffer:
Expand Down

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