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Do not assume interface numbers follow the slice indices. (#134)

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Do not assume interface numbers follow the slice indices.

This is a continuation of
9ad54830f4
which tried to solve the problem of non-contiguous interface indices;
this commit modifies another code path that had the same assumption.
This commit is contained in:
Sebastian Zagrodzki
2024-09-13 20:43:01 +02:00
committed by GitHub
parent 606016adee
commit e840be9d06
4 changed files with 91 additions and 22 deletions
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28
config.go
View File

@@ -49,25 +49,17 @@ func (c ConfigDesc) String() string {
return fmt.Sprintf("Configuration %d", c.Number)
}
func (c ConfigDesc) intfDesc(num, alt int) (*InterfaceSetting, error) {
func (c ConfigDesc) intfDesc(num int) (*InterfaceDesc, error) {
// In an ideal world, interfaces in the descriptor would be numbered
// contiguously starting from 0, as required by the specification. In the
// real world however the specification is sometimes ignored:
// https://github.com/google/gousb/issues/65
ifs := make([]int, len(c.Interfaces))
for i := range c.Interfaces {
ifs[i] = c.Interfaces[i].Number
if ifs[i] != num {
continue
for i, desc := range c.Interfaces {
if desc.Number == num {
return &desc, nil
}
alts := make([]int, len(c.Interfaces[i].AltSettings))
for a := range c.Interfaces[i].AltSettings {
alts[a] = c.Interfaces[i].AltSettings[a].Alternate
if alts[a] == alt {
return &c.Interfaces[i].AltSettings[a], nil
}
}
return nil, fmt.Errorf("alternate setting %d not found for %s, available alt settings: %v", alt, c.Interfaces[i], alts)
ifs[i] = desc.Number
}
return nil, fmt.Errorf("interface %d not found, available interface numbers: %v", num, ifs)
}
@@ -120,9 +112,13 @@ func (c *Config) Interface(num, alt int) (*Interface, error) {
return nil, fmt.Errorf("Interface(%d, %d) called on %s after Close", num, alt, c)
}
altInfo, err := c.Desc.intfDesc(num, alt)
intf, err := c.Desc.intfDesc(num)
if err != nil {
return nil, fmt.Errorf("descriptor of interface (%d, %d) in %s: %v", num, alt, c, err)
return nil, fmt.Errorf("descriptor of interface %d in %s: %v", num, c, err)
}
altInfo, err := intf.altSetting(alt)
if err != nil {
return nil, fmt.Errorf("descriptor of alternate setting %d of interface %d in %s: %v", alt, num, c, err)
}
c.mu.Lock()
@@ -137,7 +133,7 @@ func (c *Config) Interface(num, alt int) (*Interface, error) {
}
// Select an alternate setting if needed (device has multiple alternate settings).
if len(c.Desc.Interfaces[num].AltSettings) > 1 {
if len(intf.AltSettings) > 1 {
if err := c.dev.ctx.libusb.setAlt(c.dev.handle, uint8(num), uint8(alt)); err != nil {
c.dev.ctx.libusb.release(c.dev.handle, uint8(num))
return nil, fmt.Errorf("failed to set alternate config %d on interface %d of %s: %v", alt, num, c, err)